Tooling materials for molds

ABSTRACT

This invention relates generally to the fabrication of materials for use as tools in various applications. Specific emphasis is placed upon certain ceramic matrix composite materials and metal matrix composite materials for use as tools as well as certain ceramic matrix composite and/or metal matrix composite coatings on substrate materials, also for use as tools. This invention makes specific reference to a number of different materials for use as tools in the molding of thermoplastic materials (e.g., polymers, plastics, ceramics, glasses, metals) with particular emphasis being directed to the thermoplastic molding of plastics or polymers.

This a continuation-in-part of 07/622,998, filed Dec. 5, 1990, nowabandoned.

TECHNICAL INVENTION

This invention relates generally to the fabrication of materials for useas tools in various applications. Specific emphasis is placed uponcertain ceramic matrix composite materials and metal matrix compositematerials for use as tools as well as certain ceramic matrix compositeand/or metal matrix composite coatings on substrate materials, also foruse as tools. This invention makes specific reference to a number ofdifferent materials for use as tools in the molding of thermoplasticmaterials (e.g., polymers, plastics, ceramics, glasses, metals) withparticular emphasis being directed to the thermoplastic molding ofplastics or polymers.

BACKGROUND ART

The prior art is replete with numerous attempts to make various toolsfrom different materials. Tools for use in the fabrication of metals,ceramics, glasses, plastics, polymers, etc., are used primarily to shapethe aforementioned materials in a predetermined manner. Thus, simplystated, a tool can be utilized to manufacture shaped ceramic, metal,glass and/or polymer or plastic products.

Many different types of tools currently exist for plastically deformingpolymer or plastic materials. For example, tools for making shapes byblow molding, tools for making shapes by vacuum molding, compressionmolding tools, injection molding tools, tools against which materialsare contacted or layed-up, tools for vacuum lay-ups, etc., are allexamples of tools which are useful for making shaped plastics orpolymers.

While the prior art contains many exemplary tools, numerous problemsexist in tool design, as well as in the specific materials which areutilized for tools. For example, in the plastic or polymer moldingindustry, the materials utilized for tools suffer from variousdrawbacks, including short usable life times (e.g., the tools sufferfrom high wear either in localized areas or throughout the entire tool,thermal shock problems, etc. ), poor thermal conductivity, the relativeinability to match the coefficient of thermal expansion of the tool tothe formed product, unacceptably long lead time requirements for thepreparation and manufacture of tools, high machining costs associatedwith the formation of tools (e.g., especially when the tools have anintricate or complex shape), the inability to control accurately and ina cost efficient manner the localized heating and/or coolingcharacteristics of the tool, large and sometimes quite heavy andawkwardly shaped tools, substantial difficulties in replicating mastermold finishes, poor surface finishes, etc. The above-discussed problemsare just a few of the problems facing manufacturers today, any one ofwhich can result in high production costs and/or longer productiontimes.

French Patent No. 7702248 relates to a method of producing a mold foruse as part of a tool for shaping of mold or mold materials and havingrelatively high strength and heat resistance characteristics. Accordingto the invention, there is formed a porous body of sinterable materialin contact with a pattern to form a material-shaping surface of thebody; the body when still in contact with the pattern surface issintered and the sintered body is at least partially filled withinfiltrating material having a melting point lower than that of thesintered body. The infiltrating step is effected in such manner that thepores of the surface of the sintered body in contact with the patternedsurface are filled by infiltrating the material from the side of thebody opposite to the pattern surface through to the surface which isformed by the patterned surface. The sintered porous body comprises ametal body. The infiltrating material also preferably comprises a metal,although non-metallic materials are also conceivable.

WO-A-81/02126 is directed to a method of producing an article and anarticle produced in a mold which defines the contour of the article.Specifically, an article as produced in a mold which defines thecontours of the article, said article mainly consisting on the one handof sinterable material which can be given a relatively easily shapedgeometry, has the characteristics of forming a relatively porous bodyduring sintering, such as a metal powder, which material is sintered inthe mold, and on the other hand of a matrix consisting of a metal with alower melting point than the sintering temperature for the sinterablematerial, said matrix metal infiltrating the porous body so that itfills in the pores of the sintered material, at least in the moldsurface, and is molded by the mold before it is caused to solidify. Thearticle also contains one or more cooling passages consisting of a metaltube with a melting point which is higher than the sinteringtemperature, the outside of the tube being metallically connected to theinfiltrated matrix metal. In the method of producing the article, themold is filled with powder or grains of the sinterable material, so thatthe tube is embedded in the sinterable material.

The present invention overcomes the difficulties referenced above aswell as certain limitations of the prior art, and more, by providingnovel materials for use as tools as well as new and improved toolingdesigns. Thus, the present invention results in tools having desirablemechanical properties which permit the repeated and reliable manufactureof complex shaped parts in large quantities, such parts potentiallyhaving quality characteristics heretofore being unachievable in a costeffective manner.

Description of Commonly Owned U.S. Patents and Patent Applications

The subject matter of this application is related to that of severalCommonly Owned Patents and Commonly Owned and Copending PatentApplications. Particularly, these Patents and Patent Applicationsdescribe novel methods for making ceramic matrix composite materials(hereinafter sometimes referred to as "Commonly Owned Ceramic MatrixPatent Applications") and metal matrix composite materials (hereinaftersometimes referred to as "Commonly Owned Metal Matrix Patent(s) andPatent Application(s)").

A novel approach to the formation of ceramic materials is disclosedgenerically in Commonly Owned U.S. Pat. No. 4,713,360, which issued onDec. 15, 1987, in the names of Marc S. Newkirk et al., and entitled"Novel Ceramic Materials and Methods for Making Same". This Patentdiscloses a method of producing self-supporting ceramic bodies grown asthe oxidation reaction product of a molten parent precursor metal whichis reacted with a vapor-phase oxidant to form an oxidation reactionproduct. Molten metal migrates through the formed oxidation reactionproduct to react with the oxidant thereby continuously developing aceramic polycrystalline body which can, if desired, include aninterconnected metallic component. The process may be enhanced by theuse of one or more dopants alloyed with the parent metal. For example,in the case of oxidizing aluminum in air, it is desirable to alloymagnesium and silicon with the aluminum to produce alpha-alumina ceramicstructures. This method was improved upon by the application of dopantmaterials to the surface of the parent metal, as described in CommonlyOwned U.S. Pat. No. 4,853,352, which issued on Aug. 1, 1989, in thenames of Marc S. Newkirk et al., and entitled "Methods of MakingSelf-Supporting Ceramic Materials" (a European counterpart to U.S.application Ser. No. 06/747,788, now abandoned, was published in the EPOon Jan. 22, 1986, as Publication No. 0,169,067).

A novel method for producing a self-supporting ceramic composite bygrowing an oxidation reaction product from a parent metal into apermeable mass of filler is disclosed in commonly owned and copendingU.S. patent application Ser. No. 07/433,733, filed Nov. 30, 1989, andentitled "Method of Making Composite Articles Having Embedded Filler",which is a continuation-in-part of commonly owned and copending U.S.patent application Ser. No. 07/415,180, filed Sep. 29, 1989, which is adivisional U.S. Pat. No. 4,916,113, issued Apr. 10, 1990, and entitled"Methods of Making Composite Articles Having Embedded Filler", which isa continuation of U.S. Pat. No. 4,851,375, issued Jul. 25, 1989, andentitled "Composite Ceramic Articles and Methods of Making the Same",all of which are in the names of Marc S. Newkirk, et al.

A method for producing ceramic composite bodies having a predeterminedgeometry or shape is disclosed in Commonly Owned and Copending U.S.patent application Ser. No. 07/338,471, filed Apr. 14, 1989, (and nowallowed) which is a continuation of U.S. application Ser. No.06/861,025, filed May 8, 1986 (and now abandoned), both in the names ofMarc S. Newkirk et al. (a European counterpart to which was published inthe EPO on Nov. 11, 1987, as Publication No. 0,245,192). In accordancewith the method in this U.S. Patent Application, the developingoxidation reaction product infiltrates a permeable preform of fillermaterial in a direction towards a defined surface boundary. It wasdiscovered that high fidelity is more readily achieved by providing thepreform with a barrier means, as disclosed in Commonly Owned U.S. patentapplication Ser. No. 07/295,488, filed Jan. 10, 1989, which is acontinuation of U.S. Pat. No. 4,923,832, which issued May 8, 1990, bothin the names of Marc S. Newkirk et al. (a European counterpart to U.S.Pat. No. 4,923,832 was published in the EPO on Nov. 11, 1987, asPublication No. 0,245,193). This method produces shaped self-supportingceramic bodies, including shaped ceramic composites, by growing theoxidation reaction product of a parent metal to a barrier means spacedapart from the metal for establishing a boundary or surface.

Ceramic composites having a cavity with an interior geometry inverselyreplicating the shape of a positive mold or pattern are disclosed in (i)Commonly Owned U.S. patent application Ser. No. 07/329,794, filed Mar.28, 1989, (and now allowed) which is a divisional of U.S. Pat. No.4,828,785, which issued May 9, 1989, both in the names of Marc S.Newkirk, et al., a European counterpart to which was published in theEPO on Sep. 2, 1987, as Publication No. 0,234,704, and (ii) in U.S. Pat.No. 4,859,640, which issued on Aug. 22, 1989, a European counterpart towhich was published in the EPO on Mar. 9, 1988, as Publication No.0,259,239.

The feeding of additional molten parent metal from a reservoir has beensuccessfully utilized to produce thick ceramic matrix compositestructures. Particularly, as disclosed in Commonly Owned U.S. Pat. No.4,918,034, issued Apr. 17, 1990, which is a continuation-in-part of U.S.Pat. No. 4,900,699, issued Feb. 13, 1990, both in the names of Marc S.Newkirk et al., and entitled "Reservoir Feed Method of Making CeramicComposite Structures and Structures Made Thereby" (a Europeancounterpart to U.S. Pat. No. 4,900,699 was published in the EPO on Mar.30, 1988, as Publication No. 0,262,075), the reservoir feed method hasbeen successfully applied to form ceramic matrix composite structures.According to the method of this Newkirk et al. invention, the ceramic orceramic composite body which is produced comprises a self-supportingceramic composite structure which includes a ceramic matrix obtained bythe oxidation reaction of a parent metal with an oxidant to form apolycrystalline material. In conducting the process, a body of theparent metal and a permeable filler are oriented relative to each otherso that formation of the oxidation reaction product will occur in adirection toward and into the filler. The parent metal is described asbeing present as a first source and as a reservoir, the reservoir ofmetal communicating with the first source due to, for example, gravityflow. The first source of molten parent metal reacts with the oxidant tobegin the formation of the oxidation reaction product. As the firstsource of molten parent metal is consumed, it is replenished, preferablyby a continuous means, from the reservoir of parent metal as theoxidation reaction product continues to be produced and infiltrates thefiller. Thus, the reservoir assures that ample parent metal will beavailable to continue the process until the oxidation reaction producthas grown to a desired extent.

A method for tailoring the constituency of the metallic component of aceramic matrix composite structure is disclosed in Copending andCommonly Owned U.S. patent application Ser. No. 07/389,506, filed onAug. 2, 1989, which in turn is a continuation of U.S. patent applicationSer. No. 06/908,454, filed Sep. 17, 1986 (and now abandoned), both ofwhich are in the names of Marc S. Newkirk et al., and entitled "Methodfor In Situ Tailoring the Metallic Component of Ceramic Articles andArticles Made Thereby" (a European counterpart to U.S. patentapplication Ser. No. 06,908,454 was published in the EPO on Apr. 6,1988, as Publication No. 0,263,051).

Moreover, U.S. patent application Ser. No. 07/269,152, filed Nov. 9,1988, which is a continuation of U.S. patent application Ser. No.07/152,518, (which issued as U.S. Pat. No. 4,818,734, on Apr. 4, 1989),in the names of Robert C. Kantner et al., which was aContinuation-in-Part Application of the above-mentioned Ser. No.06/908,454, having the same title and also being Commonly Owned. ThisPatent and the above-mentioned application Ser. No. 06/908,454, disclosemethods for tailoring the constituency of the metallic component (bothisolated and interconnected) of ceramic and ceramic matrix compositebodies during formation thereof to impart one or more desirablecharacteristics to the resulting body. Thus, desired performancecharacteristics for the ceramic or ceramic composite body areadvantageously achieved by incorporating the desired metallic componentin situ, rather than from an extrinsic source, or by post-formingtechniques.

As discussed in these Commonly Owned Ceramic Matrix Patent Applicationsand Patents, novel polycrystalline ceramic materials or polycrystallineceramic composite materials are produced by the oxidation reactionbetween a parent metal and an oxidant (e.g., a solid, liquid and/or agas). In accordance with the generic process disclosed in these CommonlyOwned Ceramic Matrix Patent Applications and Patents, a parent metal(e.g., aluminum) is heated to an elevated temperature above its meltingpoint but below the melting point of its oxidation reaction product toform a body of molten parent metal which reacts upon contact with anoxidant to form the oxidation reaction product. At this temperature, theoxidation reaction product, or at least a portion thereof, is in contactwith and extends between the body of molten parent metal and theoxidant, and molten metal is drawn or transported through the formedoxidation reaction product and towards the oxidant. The transportedmolten metal forms additional fresh oxidation reaction product uponcontact with the oxidant, at the surface of previously formed oxidationreaction product. As the process continues, additional metal istransported through this formation of polycrystalline oxidation reactionproduct thereby continually "growing" a ceramic structure ofinterconnected crystallites. The resulting ceramic body may containmetallic constituents, such as non-oxidized constituents of the parentmetal, and/or voids. Oxidation is used in its broad sense in all of theCommonly Owned Ceramic Matrix Patent Applications and Patents and inthis application, and refers to the loss or sharing of electrons by ametal to an oxidant which may be one or more elements and/or compounds.Accordingly, elements other than oxygen may serve as an oxidant.

In certain cases, the parent metal may require the presence of one ormore dopants in order to influence favorably or to facilitate growth ofthe oxidation reaction product. Such dopants may at least partiallyalloy with the parent metal at some point during or prior to growth ofthe oxidation reaction product. For example, in the case of aluminum asthe parent metal and air as the oxidant, dopants such as magnesium andsilicon, to name but two of a larger class of dopant materials, can bealloyed with aluminum, and the created growth alloy is utilized as theparent metal. The resulting oxidation reaction product of such a growthalloy, in the case of using oxygen as an oxidant, comprises alumina,typically alpha-alumina.

Novel ceramic composite structures and methods of making the same arealso disclosed and claimed in certain of the aforesaid Commonly OwnedCeramic Matrix Patent Applications and Patents which utilize theoxidation reaction to produce ceramic composite structures comprising asubstantially inert filler (note: in some cases it may be desirable touse a reactive filler, e.g., a filler which is at least partiallyreactive with the advancing oxidation reaction product and/or parentmetal) infiltrated by the polycrystalline ceramic matrix. A parent metalis positioned adjacent to a mass of permeable filler (or a preform)which can be shaped and treated to be self-supporting, and is thenheated to form a body of molten parent metal which is reacted with anoxidant, as described above, to form an oxidation reaction product. Asthe oxidation reaction product grows and infiltrates the adjacent fillermaterial, molten parent metal is drawn through previously formedoxidation reaction product within the mass of filler and reacts with theoxidant to form additional fresh oxidation reaction product at thesurface of the previously formed oxidation reaction product, asdescribed above. The resulting growth of oxidation reaction productinfiltrates or embeds the filler and results in the formation of aceramic composite structure of a polycrystalline ceramic matrixembedding the filler. As also discussed above, the filler (or preform)may utilize a barrier means to establish a boundary or surface for theceramic composite structure.

Thus, the aforesaid Commonly Owned Ceramic Matrix Patent Applicationsand Patents describe the production of oxidation reaction products whichare readily grown to desired sizes and thicknesses heretofore believedto be difficult, if not impossible, to achieve with conventional ceramicprocessing techniques.

The production of boride-containing materials has been addressed incommonly owned U.S. Pat. No. 4,885,130 (hereinafter "Patent '130"),which issued Dec. 5, 1989, in the names of T. Dennis Claar, Steven M.Mason, Kevin P. Pochopien, Danny R. White, and William B. Johnson, andis entitled "Process for Preparing Self-Supporting Bodies and ProductsMade Thereby" (a European counterpart to U.S. Pat. No. 4,885,130 waspublished in the EPO on Jul. 18, 1990, as Publication No. 0,378,499).

Briefly summarizing the disclosure of Patent '130, self-supportingceramic bodies are produced by utilizing a parent metal infiltration andreaction process (i.e., reactive infiltration) in the presence of a masscomprising boron carbide. Particularly, a bed or mass comprising boroncarbide and, optionally, one or more of a boron donor material and acarbon donor material is infiltrated by molten parent metal, and the bedmay be comprised entirely of boron carbide or only partially of boroncarbide, thus resulting in a self-supporting body comprising, at leastin part, one or more parent metal boron-containing compounds, whichcompounds include a parent metal boride or a parent metal boro carbide,or both, and typically also may include a parent metal carbide. It isalso disclosed that the mass comprising boron carbide which is to beinfiltrated may also contain one or more inert fillers mixed with theboron carbide. Accordingly, by combining an inert filler, the resultwill be a composite body having a matrix produced by the reactiveinfiltration of the parent metal, said matrix comprising at least oneboron-containing compound, and the matrix may also include a parentmetal carbide, the matrix embedding the inert filler. It is furthernoted that the final composite body product in either of theabove-discussed embodiments (i.e., filler or no filler) may include aresidual metal as at least one metallic constituent of the originalparent metal.

Broadly, in the disclosed method of Patent '130, a mass comprising boroncarbide and, optionally, one or more of a boron donor material and acarbon donor material, is placed adjacent to or in contact with a bodyof molten metal or metal alloy, which is melted in a substantially inertenvironment within a particular temperature envelope. The molten metalinfiltrates the mass comprising boron carbide and reacts with at leastthe boron carbide to form at least one reaction product. The boroncarbide and/or the boron donor material and/or the carbon donor materialare reducible, at least in part, by the molten parent metal, therebyforming the parent metal boron-containing compound (e.g., a parent metalboride and/or boro compound under the temperature conditions of theprocess). Typically, a parent metal carbide is also produced, and incertain cases, a parent metal boro carbide is produced. At least aportion of the reaction product is maintained in contact with the metal,and molten metal is drawn or transported toward the unreacted masscomprising boron carbide by a wicking or a capillary action. Thistransported metal forms additional parent metal, boride, carbide, and/orboro carbide and the formation or development of a ceramic body iscontinued until either the parent metal or mass comprising boron carbidehas been consumed, or until the reaction temperature is altered to beoutside of the reaction temperature envelope. The resulting structurecomprises one or more of a parent metal boride, a parent metal borocompound, a parent metal carbide, a metal (which, as discussed in Patent'130, is intended to include alloys and intermetallics), or voids, orany combination thereof. Moreover, these several phases may or may notbe interconnected in one or more dimensions throughout the body. Thefinal volume fractions of the boron-containing compounds (i.e., borideand boron compounds), carbon-containing compounds, and metallic phases,and the degree of interconnectivity, can be controlled by changing oneor more conditions, such as the initial density of the mass comprisingboron carbide, the relative amounts of boron carbide and parent metal,alloys of the parent metal, dilution of the boron carbide with a filler,the amount of boron donor material and/or carbon donor material mixedwith the mass comprising boron carbide, temperature, and time.Preferably, conversion of the boron carbide to the parent metal boride,parent metal boro compound(s) and parent metal carbide is at least about50%, and most preferably at least about 90%.

The typical environment or atmosphere which was utilized in Patent '130was one which is relatively inert or unreactive under the processconditions. Particularly, it was disclosed that an argon gas, or avacuum, for example, would be suitable process atmospheres. Stillfurther, it was disclosed that when zirconium was used as the parentmetal, the resulting composite comprised zirconium diboride, zirconiumcarbide, and residual zirconium metal. It was also disclosed that whenaluminum parent metal was used with the process, the result was analuminum boro carbide such as Al₃ B₄₈ C₂, AlB₁₂ C₂ and/or AlB₂₄ C₄, withaluminum parent metal and other unreacted unoxidized constituents of theparent metal remaining. Other parent metals which were disclosed asbeing suitable for use with the processing conditions included silicon,titanium, hafnium, lanthanum, iron, calcium, vanadium, niobium,magnesium, and beryllium.

Still further, it is disclosed that by adding a carbon donor material(e.g., graphite powder or carbon black) and/or a boron donor material(e.g., a boron powder, silicon borides, nickel borides and iron borides)to the mass of boron carbide, the ratio or parent metal-boride/parentmetal-carbide can be adjusted. For example, if zirconium is used as theparent metal, the ratio of ZrB₂ /ZrC can be reduced if a carbon donormaterial is utilized (i.e., more ZrC is produced out to the addition ofa carbon donor material in the mass of boron carbide) while if a borondonor material is utilized, the ratio of ZrB₂ /ZrC can be increased(i.e., more ZrB₂ is produced due to the addition of a boron donormaterial in the mass of boron carbide). Still further, the relative sizeof ZrB₂ platelets which are formed in the body may be larger thanplatelets that are formed by a similar process without the use of aboron donor material. Thus, the addition of a carbon donor materialand/or a boron donor material may also effect the morphology of theresultant material.

In another related patent, specifically, U.S. Pat. No. 4,915,736(hereinafter referred to as "Patent '736"), issued in the names of TerryDennis Claar and Gerhard Hans Schiroky, on Apr. 10, 1990, and entitled"A Method of Modifying Ceramic Composite Bodies By a CarburizationProcess and Articles Made Thereby" (a European counterpart to U.S. Pat.No. 4,915,736 was published in the EPO on Jun. 28, 1989, as PublicationNo. 0,322,346), additional modification techniques are disclosed.Specifically, Patent '736 discloses that a ceramic composite body madein accordance with the teachings of, for example, Patent '130 can bemodified by exposing the composite to a gaseous carburizing species.Such a gaseous carburizing species can be produced by, for example,embedding the composite body in a graphitic bedding and reacting atleast a portion of the graphitic bedding with moisture or oxygen in acontrolled atmosphere furnace. However, the furnace atmosphere shouldcomprise typically, primarily, a non-reactive gas such as argon. It isnot clear whether impurities present in the argon gas supply thenecessary O₂ for forming a carburizing species, or whether the argon gasmerely serves as a vehicle which contains impurities generated by sometype of volatilization of components in the graphitic bedding or in thecomposite body. In addition, a gaseous carburizing species could beintroduced directly into a controlled atmosphere furnace during heatingof the composite body.

Once the gaseous carburizing species has been introduced into thecontrolled atmosphere furnace, the setup should be designed in such amanner to permit the carburizing species to be able to contact at leasta portion of the surface of the composite body buried in the looselypacked graphitic powder. It is believed that carbon in the carburizingspecies, or carbon from the graphitic bedding, will dissolve into theinterconnected zirconium carbide phase, which can then transport thedissolved carbon throughout substantially all of the composite body, ifdesired, by a vacancy diffusion process. Moreover, Patent '736 disclosesthat by controlling the time, the exposure of the composite body to thecarburizing species and/or the temperature at which the carburizationprocess occurs, a carburized zone or layer can be formed on the surfaceof the composite body. Such process could result in a hard,wear-resistant surface surrounding a core of composite material having ahigher metal content and higher fracture toughness.

Thus, if a composite body was formed having a residual parent metalphase in the amount of between about 5-30 volume percent, such compositebody could be modified by a post-carburization treatment to result infrom about 0 to about 2 volume percent, typically about 1/2 to about 2volume percent, of parent metal remaining in the composite body.

Still further, Copending U.S. patent application Ser. No. 07/296,239,filed on Jan. 12, 1989, is a continuation-in-part application of Patent'736 and discloses that in addition to a carburizing species, anitriding and/or boriding species may also be utilized to result insimilar modifications to the formed composite bodies.

In another somewhat relevant patent application, namely, U.S. patentapplication Ser. No. 07/543,316, filed on Jun. 25, 1990, in the names ofTerry Dennis Claar et al., entitled "Methods for Making Self-SupportingComposite Bodies and Articles Produced Thereby", methods for causing avapor-phase parent metal to react with a solid oxidant to form a solidreaction product are disclosed. Specifically, in preferred embodimentsof the invention, a material, at least a portion of which comprises asolid oxidant, is placed into a reaction chamber. The reaction chambershould be made of, or at least coated with, a material which does notadversely react with any of the materials utilized in the process of theinvention. A vapor-phase parent metal source is housed within thereaction chamber in a manner which permits an interaction between theparent metal vapor and the solid oxidant-containing material. Thus, theparent metal vapor should be capable of contacting that portion of thesolid oxidant-containing material which is to react with the parentmetal vapor. Accordingly, only a portion of a solid oxidant-containingmaterial may need to be exposed to the parent metal vapor orsubstantially all of a solid oxidant-containing material can be exposedto a parent metal vapor to create reaction product at selectedlocations. Accordingly, a substrate material, at least a portion ofwhich contains a solid oxidant material, could be coated with reactionproduct. Such coating may possess desirable mechanical propertiesenhancing the utilization of the substrate material for particularapplications.

A further patent application, U.S. Ser. No. 07/543,277, filed on Jun.25, 1990, in the name of Terry Dennis Claar and entitled "Method forForming a Surface Coating", discloses that a solid oxidant source and aparent metal source (e.g., a solid source and/or vapor source) arecaused to react on the surface of a substrate material to form a ceramicor ceramic composite coating. Specifically, in a first preferredembodiment of the invention, a substrate material, which may or may notbe reactive with a powdered parent metal, is coated with a mixture ofpowdered parent metal and a solid oxidant powder. The powdered parentmetal and solid oxidant powder are caused to react with each other byelevating the temperature in the reaction chamber to the reactiontemperature. In a second preferred embodiment of the invention, asubstantially inert filler material is mixed with a mixture of apowdered parent metal and a solid oxidant powder prior to causing thepowdered parent metal and solid oxidant powder to react together to forma reaction product. Accordingly, products produced according to thisinvention can be coatings on substrate materials, said coatingsresulting in enhanced performance of the substrate material in variousenvironments.

A novel method of making a metal matrix composite material is disclosedin Commonly Owned U.S. Pat. No. 4,828,008, issued May 9, 1989, in thenames of White et al., and entitled "Metal Matrix Composites". Accordingto the method of the White et al. invention, a metal matrix composite isproduced by infiltrating a permeable mass of filler material (e.g., aceramic or a ceramic-coated material) with molten aluminum containing atleast about 1 percent by weight magnesium, and preferably at least about3 percent by weight magnesium. Infiltration occurs spontaneously withoutthe application of external pressure or vacuum. A supply of the moltenmetal alloy is contacted with the mass of filler material at atemperature of at least about 675° C. in the presence of a gascomprising from about 10 to 100 percent, and preferably at least about50 percent, nitrogen by volume, and a remainder of the gas, if any,being a nonoxidizing gas, e.g., argon. Under these conditions, themolten aluminum alloy infiltrates the ceramic mass under normalatmospheric pressures to form an aluminum (or aluminum alloy) matrixcomposite. When the desired amount of filler material has beeninfiltrated with the molten aluminum alloy, the temperature is loweredto solidify the alloy, thereby forming a solid metal matrix structurethat embeds the reinforcing filler material. Usually, and preferably,the supply of molten alloy delivered will be sufficient to permit theinfiltration to proceed essentially to the boundaries of the mass offiller material. The amount of filler material in the aluminum matrixcomposites produced according to the White et al. invention may beexceedingly high. In this respect, filler to alloy volumetric ratios ofgreater than 1:1 may be achieved.

Under the process conditions in the aforesaid White et al. invention,aluminum nitride can form as a discontinuous phase dispersed throughoutthe aluminum matrix. The amount of nitride in the aluminum matrix mayvary depending on such factors as temperature, alloy composition, gascomposition and filler material. Thus, by controlling one or more suchfactors in the system, possible to tailor certain properties of thecomposite. For some end use applications, however, it may be desirablethat the composite contain little or substantially no aluminum nitride.

It has been observed that higher temperatures favor infiltration butrender the process more conducive to nitride formation. The White et al.invention allows the choice of a balance between infiltration kineticsand nitride formation.

An example of suitable barrier means for use with metal matrix compositeformation is described in Commonly Owned U.S. Pat. No. 4,935,055, issuedJun. 19, 1990, in the names of Michael K. Aghajanian et al., andentitled "Method of Making Metal Matrix Composite with the Use of aBarrier" (a European counterpart to U.S. Pat. No. 4,935,055 waspublished in the EPO on Jul. 12, 1989, as Publication No. 0,323,945).According to the method of this Aghajanian et al. invention, a barriermeans (e.g., particulate titanium diboride or a graphite material suchas a flexible graphite tape product sold by Union Carbide under thetrade name GRAFOIL®) is disposed on a defined surface boundary of afiller material and matrix alloy infiltrates up to the boundary definedby the barrier means. The barrier means is used to inhibit, prevent, orterminate infiltration of the molten alloy, thereby providing net, ornear net, shapes in the resultant metal matrix composite. Accordingly,the formed metal matrix composite bodies have an outer shape whichsubstantially corresponds to the inner shape of the barrier means.

The method of U.S. Pat. No. 4,828,008, was improved upon by CommonlyOwned and Copending U.S. patent application Ser. No. 07/517,541, filedApr. 24, 1990, which is a Continuation of U.S. patent application Ser.No. 07/168,284, filed Mar. 15, 1988 (and now abandoned), both in thenames of Michael K. Aghajanian and Marc S. Newkirk and entitled "MetalMatrix Composites and Techniques for Making the Same" (a counterpart toU.S. Pat. No. 4,828,008 was published in the EPO on Nov. 17, 1988, asPublication No. 0,291,441). In accordance with the methods disclosed inthis U.S. Patent Application, a matrix metal alloy is present as a firstsource of metal and as a reservoir of matrix metal alloy whichcommunicates with the first source of molten metal due to, for example,gravity flow. Particularly, under the conditions described in thispatent application, the first source of molten matrix alloy begins toinfiltrate the mass of filler material under normal atmosphericpressures and thus begins the formation of a metal matrix composite. Thefirst source of molten matrix metal alloy is consumed during itsinfiltration into the mass of filler material and, if desired, can bereplenished, preferably by a continuous means, from the reservoir ofmolten matrix metal as the spontaneous infiltration continues. When adesired amount of permeable filler has been spontaneously infiltrated bythe molten matrix alloy, the temperature is lowered to solidify thealloy, thereby forming a solid metal matrix structure that embeds thereinforcing filler material. It should be understood that the use of areservoir of metal is simply one embodiment of the invention describedin this patent application and it is not necessary to combine thereservoir embodiment with each of the alternate embodiments of theinvention disclosed therein, some of which could also be beneficial touse in combination with the present invention.

The reservoir of metal can be present in an amount such that it providesfor a sufficient amount of metal to infiltrate the permeable mass offiller material to a predetermined extent. Alternatively, an optionalbarrier means can contact the permeable mass of filler on at least oneside thereof to define a surface boundary.

Moreover, while the supply of molten matrix alloy delivered should be atleast sufficient to permit spontaneous infiltration to proceedessentially to the boundaries (e.g., barriers) of the permeable mass offiller material, the amount of alloy present in the reservoir couldexceed such sufficient amount so that not only will there be asufficient amount of alloy for complete infiltration, but excess moltenmetal alloy could remain and be attached to the metal matrix compositebody. Thus, when excess molten alloy is present, the resulting body willbe a complex composite body (e.g., a macrocomposite), wherein aninfiltrated ceramic body having a metal matrix therein will be directlybonded to excess metal remaining in the reservoir.

Further improvements in metal matrix technology can be found in commonlyowned and copending U.S. patent application Ser. No. 07/521,043, filedMay 9, 1990, which is a continuation-in-part of U.S. patent applicationSer. No. 07/484,753, filed Feb. 23, 1990, which is acontinuation-in-part of U.S. patent application Ser. No. 07/432,661,filed Nov. 7, 1989 (and now abandoned), which is a continuation-in-partof U.S. patent application Ser. No. 07/416,327, filed Oct. 6, 1989 (andnow abandoned), in the names of Aghajanian, et al., and entitled "AMethod of Forming Metal Matrix Composite Bodies by a SpontaneousInfiltration Process, and Products Produced Therefrom". According tothis Aghajanian, et al. invention, spontaneous infiltration of a matrixmetal into a permeable mass of filler material or preform, at least atsome point during the process, which permits molten matrix metal tospontaneously infiltrate the filler material or preform. Aghajanian, etal., disclose a number of matrix metal/infiltration enhancerprecursor/infiltrating atmosphere systems which exhibit spontaneousinfiltration. Specifically, Aghajanian, et al. disclose that spontaneousinfiltration behavior has been observed in thealuminum/magnesium/nitrogen system; the aluminum/strontium/nitrogensystem; the aluminum/zinc/oxygen system; and thealuminum/calcium/nitrogen system. However, it is clear from thedisclosure set forth in the Aghajanian, et al., invention that thespontaneous infiltration behavior should occur in other matrixmetal/infiltration enhancer precursor/infiltrating atmosphere systems.

A novel method of forming a metal matrix composite by infiltration of apermeable mass of filler contained in a ceramic matrix composite mold isdisclosed in Commonly Owned U.S. Pat. No. 4,871,008, issued Oct. 3,1989, which issued from U.S. patent application Ser. No. 07/142,385,filed Jan. 11, 1988, by Dwivedi et al., both entitled "Method of MakingMetal Matrix Composites" (a European counterpart to U.S. Pat. No.4,871,008 was published in the EPO on Jul. 19, 1989, as Publication No.0,324,706). According to the method of the Dwivedi et al. invention, amold is formed by the directed oxidation of a molten precursor metal orparent metal with an oxidant to develop or grow a polycrystallineoxidation reaction product which embeds at least a portion of a preformcomprised of a suitable filler (referred to as a "first filler"). Theformed mold of ceramic matrix composite is then provided with a secondfiller and the second filler and mold are contacted with molten metal,and the mold contents are hermetically sealed, most typically byintroducing at least one molten metal into the entry or opening whichseals the mold. The hermetically sealed bedding may contain entrappedair, but the entrapped air and the mold contents are isolated or sealedso as to exclude or shut-out the external or ambient air. By providing ahermetic environment, effective infiltration of the second filler atmoderate molten metal temperatures is achieved, and therefore obviatesor eliminates any necessity for wetting agents, special alloyingingredients in the molten matrix metal, applied mechanical pressure,applied vacuum, special gas atmospheres or other infiltrationexpedients.

The above-discussed commonly owned patent describes a method for theproduction of a metal matrix composite body, which may be bonded to aceramic matrix composite body, and the novel bodies which are producedtherefrom.

A method of forming macrocomposite bodies by a somewhat related processis disclosed in Commonly Owned and Copending U.S. patent applicationSer. No. 07/484,575, filed on Feb. 23, 1990, in the names of Marc S.Newkirk et al., and entitled "Methods for Forming Macrocomposite Bodiesand Macrocomposite Bodies Produced Thereby". This application is acontinuation-in-part application of application Ser. No. 07/405,747,filed Sep. 11, 1989, in the names of Marc S. Newkirk et al., andentitled "Methods for Forming Macrocomposite Bodies and MacrocompositeBodies Produced Thereby", which in turn is a continuation-in-partapplication of application Ser. No. 07/376,416, filed on Jul. 7, 1989,which is a continuation-in-part of U.S. patent application Ser. No.07/368,564, filed on Jun. 20, 1989, which is in turn acontinuation-in-part of U.S. patent application Ser. No. 07/269,464,filed on Nov. 10, 1988, all in the names of Marc S. Newkirk et al., andentitled "Methods for Forming Macrocomposite Bodies and MacrocompositeBodies Produced Thereby" (a European counterpart to U.S. applicationSer. No. 07/269,464 was published in the EPO on May 23, 1990, asPublication No. 0,369,931). These applications disclose various methodsrelating to the formation of macrocomposite bodies by spontaneouslyinfiltrating a permeable mass of filler material or a preform withmolten matrix metal and bonding the spontaneously infiltrated materialto at least one second material such as a ceramic and/or a metal.Particularly, an infiltration enhancer and/or infiltration enhancerprecursor and/or infiltrating atmosphere are in communication with afiller material or a preform, at least at some point during the process,which permits molten matrix metal to spontaneously infiltrate the fillermaterial or preform. Moreover, prior to infiltration, the fillermaterial or preform is placed into contact with at least a portion of asecond material such that after infiltration of the filler material orpreform, the infiltrated material is bonded to the second material,thereby forming a macrocomposite body.

A method of forming metal matrix composite bodies by a self-generatedvacuum process similar to the process of the instant invention isdisclosed in Commonly Owned and Copending U.S. patent application Ser.No. 07/381,523, filed on Jul. 18, 1989, in the names of Robert C.Kantner et al., and entitled "A Method of Forming Metal Matrix CompositeBodies by a Self-Generated Vacuum Process and Products ProducedTherefrom". This patent application discloses a method whereby a moltenmatrix metal is contacted with a filler material or a preform in thepresence of a reactive atmosphere, and, at least at some point duringthe process, the molten matrix metal reacts, either partially orsubstantially completely, with the reactive atmosphere, thereby causingthe molten matrix metal to infiltrate the filler material or preform dueto, at least in part, the creation of a self-generated vacuum. Suchself-generated vacuum infiltration occurs without the application of anyexternal pressure or vacuum.

A method of forming macrocomposite bodies by self-generated vacuumprocess, similar to the process of the instant invention, is disclosedin Commonly Owned and Copending U.S. patent application Ser. No.07/560,746, filed Jul. 31, 1990, which is a Continuation-In-Part of U.S.patent application Ser. No. 07/383,953, filed Jul. 21, 1989, in thenames of Robert C. Kantner et al., and entitled "A Method of FormingMacrocomposite Bodies by Self-Generated Vacuum Techniques and ProductsProduced Therefrom". This patent application discloses a method, wherebya molten matrix metal is contacted with a filler material or a preformor a second body in the presence of a reactive atmosphere, and at leastat some point during the process, the molten matrix metal reacts, eitherpartially or substantially completely, with the reactive atmosphere,thereby causing the molten matrix metal to infiltrate the fillermaterial or preform contacting a second body due to, at least in part,the creation of a self-generated vacuum. Such self-generated vacuuminfiltration occurs without the application of any external pressure orvacuum.

The entire disclosures of the above-described commonly owned patents andpatent applications are expressly incorporated herein by reference.

DISCLOSURE OF THE INVENTION

The present invention relates to the unexpected discovery of a number ofnovel materials which can be utilized as tool materials for thethermoplastic formation of a number of different materials.Specifically, materials such as metals, ceramics, glasses, plastics, andpolymers can be thermoplastically deformed under the appropriate processconditions. However, such thermoplastic deforming techniques placestringent requirements upon tools which are utilized for thermoplasticdeformation.

This invention provides a number of novel materials for use as tools forvarious plastic formation processes. In particular, the ability toengineer the physical properties of the materials of the invention tomeet various needs of the tooling industry provides significantadvantages over tools previously known in the art. Physicalcharacteristics including wear resistance, thermal conductivity, thermalexpansion coefficient, etc., are all capable of being engineered in amanner which maximizes the potential for the materials of the inventionto be utilized as tools.

Still further, because of the ability of the materials of the inventionto be formed to net or near net shapes, many disadvantages of the priorart associated with the actual manufacture of tools are overcome.

The present invention satisfies a long felt need in the tooling industryfor providing tools which can produce reliably, large numbers of formedor shaped products.

The present invention also provides for the ability to locate heatingand/or cooling channels within selected locations within a tool tomaximize the production of parts and/or the mechanical properties ofparts produced by a tool.

Definitions

"Active Filler", as used herein, means fillers which provide nucleationsites and/or act as catalysts for ceramic matrix formation.

"Alloy Side" as used herein, in conjunction with ceramic matrixcomposite, refers to that side of the ceramic matrix composite whichinitially contacted molten metal before the oxidation reaction productof that molten metal and an oxidant infiltrated the preform or mass offiller material.

In conjunction with metal matrix composite, refers to that side of ametal matrix composite which initially contacted molten matrix metalbefore that molten metal infiltrated the permeable mass of fillermaterial or preform.

"Aluminum", as used herein, means and includes essentially pure metal(e.g., relatively pure, commercially available unalloyed aluminum) orother grades of metal and metal alloys such as the commerciallyavailable metals having impurities and/or alloying constituents such asiron, silicon, copper, magnesium, manganese, chromium, zinc, etc.,therein. An aluminum alloy for purposes of this definition is an alloyor intermetallic compound in which aluminum is the major constituent.

"Ambient Atmosphere", as used herein, refers to the atmosphere outsidethe filler material or preform and the impermeable container. It mayhave substantially the same constituents as the reactive atmosphere, orit may have different constituents.

"Balance Non-Oxidizing Gas", as used herein, means that any gas presentin addition to the primary or oxidizing gas (if utilized) comprising thevapor-phase oxidant or infiltrating atmosphere that is either an inertgas or a reducing gas which is substantially non-reactive with theparent metal or matrix metal under the process conditions. Any oxidizinggas which may be present as an impurity in the gas(es) used should beinsufficient to oxidize the parent metal or matrix metal to anysubstantial extent under the process conditions.

"Barrier" or "barrier means", as used herein in conjunction with ceramicmatrix composite bodies, means any material, compound, element,composition, or the like, which, under the process conditions, maintainssome integrity, is not substantially volatile (i.e., the barriermaterial does not volatilize to such an extent that it is renderednon-functional as a barrier) and is preferably permeable to avapor-phase oxidant (if utilized) while being capable of locallyinhibiting, poisoning, stopping, interfering with, preventing, or thelike, continued growth of the oxidation reaction product.

"Barrier" or "barrier means", as used herein, in conjunction with metalmatrix composite bodies, means any suitable means which interferes,inhibits, prevents or terminates the migration, movement, or the like,of molten matrix metal beyond a surface boundary of a permeable mass offiller material or preform, where such surface boundary is defined bysaid barrier means. Suitable barrier means may be any such material,compound, element, composition, or the like, which, under the processconditions, maintains some integrity and is not substantially volatile(i.e., the barrier material does not volatilize to such an extent thatit is rendered non-functional as a barrier).

Further, suitable "barrier means" includes materials which are eitherwettable or non-wettable by the migrating molten matrix metal under theprocess conditions employed, so long as wetting of the barrier meansdoes not proceed substantially beyond the surface of the barriermaterial (i.e., surface wetting). A barrier of this type appears toexhibit substantially little or no affinity for the molten matrix metal,and movement beyond the defined surface boundary of the mass of fillermaterial or preform is prevented or inhibited by the barrier means. Thebarrier reduces any final machining or grinding that may be required anddefines at least a portion of the surface of the resulting metal matrixcomposite product.

"Bonded", as used herein, means any method of attachment between twobodies. The attachment may be physical and/or chemical and/ormechanical. A physical attachment requires that at least one of the twobodies, usually in a liquid state, infiltrates at least a portion of themicrostructure of the other body. This phenomenon is commonly known as"wetting". A chemical attachment requires that at least one of the twobodies chemically react with the other body to form at least onechemical bond between the two bodies. One method of forming a mechanicalattachment between the two bodies includes a macroscopic infiltration ofat least one of the two bodies into the interior of the other body. Anexample of this would be the infiltration of at least one of the twobodies into a groove or slot on the surface of the other body. Suchmechanical attachment does not include microscopic infiltration or"wetting" but may be used in combination with such physical attachmenttechniques.

An additional method of mechanical attachment includes such techniquesas "shrink fitting", wherein one body is attached to the other body by apressure fit. In this method of mechanical attachment, one of the bodieswould be placed under compression by the other body.

"Bronze", as used herein, means and includes a copper rich alloy, whichmay include iron, tin, zinc, aluminum, silicon, beryllium, manganeseand/or lead. Specific bronze alloys include those alloys in which theproportion of copper is about 90% by weight, the proportion of siliconis about 6% by weight, and the proportion of iron is about 3% by weight.

"Carcass" or "Parent Metal Carcass", as used herein, in conjunction withceramic matrix composites, refers to any of the original body of parentmetal remaining which has not been consumed during formation of theceramic body, or the ceramic composite body, and typically, whichremains in at least partial contact with the formed body. It should beunderstood that the carcass may also typically include some oxidizedconstituents of the parent metal and/or a second or foreign metaltherein.

"Carcass" or "Carcass of Matrix Metal", as used herein, in conjunctionwith metal matrix composites, refers to any of the original body ofmatrix metal remaining which has not been consumed during formation ofthe metal matrix composite body, and typically, if allowed to cool,remains in at least partial contact with the metal matrix composite bodywhich has been formed. It should be understood that the carcass may alsoinclude a second or foreign metal therein.

"Cast Iron", as used herein, refers to the family of cast ferrous alloyswherein the proportion of carbon is at least about 2% by weight.

"Ceramic", as used herein, should not be unduly construed as beinglimited to a ceramic body in the classical sense, that is, in the sensethat it consists entirely of non-metallic and inorganic materials, butrather refers to a body which is predominantly ceramic with respect toeither composition or dominant properties, although the body may containminor or substantial amounts of one or more metallic constituents(isolated and/or interconnected, depending on the processing conditionsused to form the body) derived from the parent metal, or reduced fromthe oxidant or a dopant, most typically within a range of from about1-40 percent by volume, but may include still more metal.

"Ceramic Matrix Composite" or "CMC" or "Ceramic Composite Body", as usedherein, means a material comprising a two- or three-dimensionallyinterconnected ceramic which has embedded a preform or filler material,and may further include a parent metal phase embedded therein, possiblyin a two- or three-dimensionally interconnected network. The ceramic mayinclude various dopant elements to provide a specifically desiredmicrostructure, or specifically desired mechanical, physical, orchemical properties in the resulting composite.

"Copper", as used herein, refers to the commercial grades of thesubstantially pure metal, e.g., 99% by weight copper with varyingamounts of impurities contained therein. Moreover, it also refers tometals which are alloys or intermetallics which do not fall within thedefinition of bronze, and which contain copper as the major constituenttherein.

"Dopants", as used herein, means materials (parent metal constituents orconstituents combined with and/or included in or on a filler, orcombined with the oxidant) which, when used in combination with theparent metal, favorably influence or promote the oxidation reactionprocess and/or modify the growth process to alter the microstructureand/or properties of the product. While not wishing to be bound by anyparticular theory or explanation of the function of dopants, it appearsthat some dopants are useful in promoting oxidation reaction productformation in cases where appropriate surface energy relationshipsbetween the parent metal and its oxidation reaction product do notintrinsically exist so as to promote such formation. Dopants may beadded to the filler material, they may be in the form of a gas, solid,or liquid under the process conditions, they may be included asconstituents of the parent metal, or they may be added to any one of theconstituents involved in the formation of the oxidation reactionproduct. Dopants may: (1) create favorable surface energy relationshipswhich enhance or induce the wetting of the oxidation reaction product bythe molten parent metal; and/or (2) form a "precursor layer" at thegrowth surface by reaction with alloy, oxidant, and/or filler, that (a)minimizes formation of a protective and coherent oxidation reactionproduct layer(s), (b) may enhance oxidant solubility (and thuspermeability) in molten metal, and/or (c) allows for transport ofoxidant from the oxidizing atmosphere through any precursor oxide layerto combine subsequently with the molten metal to form another oxidationreaction product; and/or (3) cause microstructural modifications of theoxidation reaction product as it is formed or subsequently and/or alterthe metallic constituent composition and properties of such oxidationreaction product; and/or (4) enhance growth nucleation and uniformity ofgrowth of oxidation reaction product.

"Excess Matrix Metal" or "Residual Matrix Metal", as used herein, inconjunction with metal matrix composites, means that quantity or amountof matrix metal which remains after a desired amount of spontaneousinfiltration into a filler material or preform has been achieved andwhich is intimately bonded to the formed metal matrix composite. Theexcess or residual matrix metal may have a composition which is the sameas or different from the matrix metal which has spontaneouslyinfiltrated the filler material or preform.

"Filler", as used herein, in conjunction with ceramic matrix composites,means either single constituents or mixtures of constituents which aresubstantially non-reactive with and/or of limited solubility in theparent metal) and/or oxidation reaction product and may be single ormulti-phase. Fillers may be provided in a wide variety of forms, such aspowders, flakes, platelets, microspheres, whiskers, bubbles, etc., andmay be either dense or porous. "Filler" may also include ceramicfillers, such as alumina or silicon carbide as fibers, chopped fibers,particulates, whiskers, bubbles, spheres, fiber mats, or the like, andcoated fillers such as carbon fibers coated with alumina or siliconcarbide to protect the carbon from attack, for example, by a moltenaluminum parent metal. Fillers may also include metals. For example,refractory metals such as tungsten, tantalum and molybdeum could be usedas fillers.

"Filler", as used herein, in conjunction with metal matrix composites,is intended to include either single constituents or mixtures ofconstituents which are substantially non-reactive with and/or of limitedsolubility in the matrix metal and may be single or multi-phase. Fillersmay be provided in a wide variety of forms, such as powders, flakes,platelets, microspheres, whiskers, bubbles, etc., and may be eitherdense or porous. "Filler" may also include ceramic fillers, such asalumina or silicon carbide as fibers, chopped fibers, particulates,whiskers, bubbles, spheres, fiber mats, or the like, and ceramic-coatedfillers such as carbon fibers coated with alumina or silicon carbide toprotect the carbon from attack, for example, by a molten aluminum parentmetal. Fillers may also include metals.

"Green", as used herein in conjunction with filler materials andpreforms, refers to a filler material or preform before any growth ofoxidation reaction product into the filler material or preform hasoccurred. Thus a filler material or preform that has been fired at anelevated temperature (for example, to volatilize a binder) should beconsidered to be "green" so long as the filler material or preform hasnot been infiltrated by either the parent metal or the oxidationreaction product.

"Growth Alloy", as used herein, in conjunction with ceramic matrixcomposites, means any alloy containing initially, or at some pointduring processing obtaining, a sufficient amount of requisiteconstituents to result in growth of oxidation reaction producttherefrom. Growth alloy may differ from a parent metal in that thegrowth alloy may include constituents not present in the parent metal,but incorporated into the molten alloy during growth.

"Impermeable Container", as used herein, means a container which mayhouse or contain a reactive atmosphere and a filler material (orpreform) and/or molten matrix metal and/or a sealing means and/or atleast a portion of at least one second material, under the processconditions, and which is sufficiently impermeable to the transport ofgaseous or vapor species through the container, such that a pressuredifference between the ambient atmosphere and the reactive atmospherecan be established.

"Infiltrating Atmosphere", as used herein, means that atmosphere whichis present which interacts with the matrix metal and/or preform (orfiller material) and/or infiltration enhancer precursor and/orinfiltration enhancer and permits or enhances spontaneous infiltrationof the matrix metal to occur.

"Infiltration Enhancer", as used herein, means a material which promotesor assists in the spontaneous infiltration of a matrix metal into afiller material or preform. An infiltration enhancer may be formed from,for example, a reaction of an infiltration enhancer precursor with aninfiltrating atmosphere to form (1) a gaseous species and/or (2) areaction product of the infiltration enhancer precursor and theinfiltrating atmosphere and/or (3) a reaction product of theinfiltration enhancer precursor and the filler material or preform.Moreover, the infiltration enhancer may be supplied directly to at leastone of the preform, and/or matrix metal, and/or infiltrating atmosphereand function in a substantially similar manner to an infiltrationenhancer which has formed as a reaction between an infiltration enhancerprecursor and another species. Ultimately, at least during thespontaneous infiltration, the infiltration enhancer should be located inat least a portion of the filler material or preform to achievespontaneous infiltration.

"Infiltration Enhancer Precursor" or "Precursor to the InfiltrationEnhancer", as used herein, means a material which when used incombination with the matrix metal, preform and/or infiltratingatmosphere forms an infiltration enhancer which induces or assists thematrix metal to spontaneously infiltrate the filler material or preform.Without wishing to be bound by any particular theory or explanation, itappears as though it may be necessary for the precursor to theinfiltration enhancer to be capable of being positioned, located ortransportable to a location which permits the infiltration enhancerprecursor to interact with the infiltrating atmosphere and/or thepreform or filler material and/or metal. For example, in some matrixmetal/infiltration enhancer precursor/infiltrating atmosphere systems,it is desirable for the infiltration enhancer precursor to volatilizeat, near, or in some cases, even somewhat above the temperature at whichthe matrix metal becomes molten. Such volatilization may lead to: (1) areaction of the infiltration enhancer precursor with the infiltratingatmosphere to form a gaseous species which enhances wetting of thefiller material or preform by the matrix metal; and/or (2) a reaction ofthe infiltration enhancer precursor with the infiltrating atmosphere toform a solid, liquid or gaseous infiltration enhancer in at least aportion of the filler material or preform which enhances wetting; and/or(3) a reaction of the infiltration enhancer precursor within the fillermaterial or preform which forms a solid, liquid or gaseous infiltrationenhancer in at least portion of the filler material or preform whichenhances wetting.

"Liquid-Phase Oxidant" or "Liquid Oxidant", as used herein, in means anoxidant in which the identified liquid is the sole, predominant or atleast a significant oxidizer of the parent or precursor metal under theconditions of the process.

Reference to a liquid oxidant means one which is a liquid under theoxidation reaction conditions. Accordingly, a liquid oxidant may have asolid precursor, such as a salt, which is molten at the oxidationreaction conditions. Alternatively, the liquid oxidant may have a liquidprecursor (e.g., a solution of a material) which is used to impregnatepart or all of the filler and which is melted or decomposed at theoxidation reaction conditions to provide a suitable oxidant moiety.Examples of liquid oxidants as herein defined include low meltingglasses.

If a liquid oxidant is employed in conjunction with the parent metal anda filler, typically, the entire bed of filler, or that portioncomprising the desired ceramic body, is impregnated with the oxidant(e.g., by coating or immersion in the oxidant).

"Macrocomposite" or "Macrocomposite Body", as used herein, means anycombination of two or more materials selected from the group consistingof a ceramic body, a ceramic matrix composite body, a metal body, and ametal matrix composite body, which are intimately bonded together in anyconfiguration, wherein at least one of the materials comprises a metalmatrix composite body formed by a self-generated vacuum technique or bya spontaneous infiltration technique, or a ceramic matrix composite bodyformed by a directed oxidation technique. The metal matrix compositebody or ceramic matrix composite body may be present as an exteriorsurface and/or as an interior surface. Further, the metal matrixcomposite body or the ceramic matrix composite body may be present as aninterlayer between two or more of the materials in the group describedabove. It should be understood that the order, number, and/or locationof a metal matrix composite body or a ceramic matrix composite body, orbodies relative to residual matrix metal or parent metal and/or any ofthe materials in the group discussed above, can be manipulated orcontrolled in an unlimited fashion.

"Matrix Metal" or "Matrix Metal Alloy", as used herein, means that metalwhich is utilized to form a metal matrix composite (e.g., beforeinfiltration) and/or that metal which is intermingled with a fillermaterial to form a metal matrix composite body (e.g., afterinfiltration). When a specified metal is mentioned as the matrix metal,it should be understood that such matrix metal includes that metal as anessentially pure metal, a commercially available metal having impuritiesand/or alloying constituents therein, an intermetallic compound or analloy in which that metal is the major or predominant constituent.

"Matrix Metal/Infiltration Enhancer Precursor/Infiltrating AtmosphereSystem" or "Spontaneous System", as used herein, refers to thatcombination of materials which exhibits spontaneous infiltration into apreform or filler material. It should be understood that whenever a "/"appears between an exemplary matrix metal, infiltration enhancerprecursor and infiltrating atmosphere that, the "/" is used to designatea system or combination of materials which, when combined in aparticular manner, exhibits spontaneous infiltration into a preform orfiller material.

"Metal Matrix Composite" or "MMC", as used herein means a materialcomprising a two- or three-dimensionally interconnected alloy or matrixmetal which has embedded a preform or filler material. The matrix metalmay include various alloying elements to provide specifically desiredmechanical and physical properties in the resulting composite.

"Nitrogen-Containing Gas Oxidant", as used herein, means a particulargas or vapor in which nitrogen is the sole, predominant or at least asignificant oxidizer of the parent or precursor metal under theconditions existing in the oxidizing environment utilized. The nitrogencould be molecular nitrogen (i.e., N₂) or could be contained in acompound such as NH₃.

"Nonreactive Vessel for Housing Matrix Metal" means any vessel which canhouse or contain molten matrix metal under the process conditions andnot react with the matrix and/or the infiltrating atmosphere and/orinfiltration enhancer precursor and/or filler material or preform in amanner which would be significantly detrimental to the spontaneousinfiltration mechanism.

"Oxidant", as used herein, means one or more suitable electron acceptorsor electron sharers and may be a solid, a liquid or a gas or somecombination of these (e.g., a solid and a gas) at the oxidation reactionconditions. Typical oxidants include, without limitation, oxygen,nitrogen, any halogen or a combination thereof, sulphur, phosphorus,arsenic, carbon, boron, selenium, tellurium, and or compounds andcombinations thereof, for example, silica or silicates (as sources ofoxygen), methane, ethane, propane, acetylene, ethylene, propylene (thehydrocarbon as a source of carbon), and mixtures such as air, H₂ /H₂ Oand CO/CO₂ (as sources of oxygen). The latter two (i.e., H₂ /H₂ O andCO/CO₂) being useful in reducing the oxygen activity of the environment.

"Oxidation", as used herein means a chemical reaction in which anoxidant reacts with a parent metal, and that parent metal has given upelectrons to or shared electrons with the oxidant.

"Oxidation Reaction Product", as used herein, means one or more metalsin any oxidized state wherein the metal(s) has given up electrons to orshared electrons with another element, compound, or combination thereof.Accordingly, an "oxidation reaction product" under this definitionincludes the product of the reaction of one or more metals with one ormore oxidants.

"Oxygen-Containing Gas Oxidant", as used herein, means a particular gasor vapor in which oxygen is the sole, predominant or at least asignificant oxidizer or the parent or precursor metal under theconditions existing in the oxidizing environment utilized.

"Parent Metal", as used herein, means that metal(s) (e.g., aluminum,silicon, titanium, tin and/or zirconium) which is the precursor of apolycrystalline oxidation reaction product (e.g., oxides, parent metalborides, or other parent metal boron compounds, etc.) and includes thatmetal(s) as an essentially pure metal, a commercially available metalhaving impurities and/or alloying constituents therein, or an alloy inwhich that metal precursor is the major constituent. When a specifiedmetal is mentioned as the parent or precursor metal (e.g., aluminum,zirconium, etc.), the metal identified should be read with thisdefinition in mind unless indicated otherwise by the context.

A Metal "Different" from the parent metal means a metal which does notcontain, as a primary constituent, the same metal as the parent metal(e.g., if the primary constituent of the parent metal is aluminum, the"different" metal could have a primary constituent of, for example,nickel).

"Parent metal boride" and "parent metal boron compounds" mean a reactionproduct containing boron formed upon reaction between boron carbide andthe parent metal and includes a binary compound of boron with the parentmetal as well as ternary or higher order compounds.

"Parent Metal Powder" as used herein, means that metal (e.g., zirconium,titanium, hafnium, etc.) which is the precursor for a reaction productof the powdered parent metal and a solid oxidant (e.g., parent metalcarbides, etc.) and includes that metal as a pure or relatively puremetal, a commercially available metal having impurities and/or alloyingconstituents therein and an alloy in which that metal precursor is themajor constituent. When a specific metal is mentioned as the powderedparent metal, the metal identified should be read with this definitionin mind unless indicated otherwise by the context.

"Parent Metal Vapor" or "Vapor-Phase Parent Metal" as used herein, meansthat metal (e.g., zirconium, titanium, hafnium) which is the vapor-phaseprecursor for the reaction product (e.g., parent metal carbides, etc.)of the parent metal and a solid oxidant and includes that metal as apure or relatively pure metal, a commercially available metal havingimpurities and/or alloying constituents therein and an alloy in whichthat metal precursor is the major constituent. When a specific metal ismentioned as the powdered parent metal, the metal identified should beread with this definition in mind unless indicated otherwise by thecontext.

"Preform" or "Permeable Preform", as used herein, means a porous mass offiller or filler material which is manufactured with at least onesurface boundary which essentially defines a boundary for infiltratingmatrix metal or oxidation reaction product, such mass retainingsufficient shape integrity and green strength to provide dimensionalfidelity without any external means of support prior to beinginfiltrated by the matrix metal or the oxidation reaction product. Themass should be sufficiently porous to permit infiltration of the matrixmetal or the oxidation reaction product. A preform typically comprises abonded array or arrangement of filler, either homogeneous orheterogeneous, and may be comprised of any suitable material (e.g.,ceramic and/or metal particulates, powders, fibers, whiskers, etc., andany combination thereof). A preform may exist either singularly or as anassemblage.

"Product Releasers", as used herein, means materials that facilitate therelease of the ceramic matrix composite from the parent metal carcassafter growth is substantially completed.

"Reaction System", as used herein, refers to that combination ofmaterials which exhibit self-generated vacuum infiltration of a moltenmatrix metal into a filler material or preform. A reaction systemcomprises at least an impermeable container having therein a permeablemass of filler material or preform, a reactive atmosphere and a matrixmetal.

"Reactive Atmosphere", as used herein, means an atmosphere which mayreact with the matrix metal and/or filler material (or preform) and/orimpermeable container to form a self-generated vacuum, thereby causingmolten matrix metal to infiltrate into the filler material (or preform)upon formation of the self-generated vacuum.

"Reactive Filler" means that the filler interacts with molten parentmetal or molten matrix metal (e.g., is reduced by the parent metaland/or oxidation reaction product and thus modifies the composition ofthe parent metal and/or provides an oxidant for formation of theoxidation reaction product).

"Reservoir", as used herein, in conjunction with ceramic matrixcomposites, means a separate body of parent metal positioned relative toa mass of filler or a preform so that, when the metal is molten, thereservoir may flow to replenish, or in some cases to initially provideand subsequently replenish, that portion, segment or source of parentmetal which is in contact with the filler or preform and infiltratingand/or reacting to form the oxidation reaction product. The reservoirmay also be used to provide a metal which is different from the parentmetal.

"Reservoir", as used herein, in conjunction with metal matrixcomposites, means a separate body of matrix metal positioned relative toa mass of filler or a preform so that, when the metal is molten, it mayflow to replenish, or in some cases to initially provide andsubsequently replenish, that portion, segment or source of matrix metalwhich is in contact with the filler or preform.

"Seal" or "Sealing Means", as used herein, refers to a gas-impermeableseal under the process conditions, whether formed independent of (e.g.,an extrinsic seal) or formed by the reaction system (e.g., an intrinsicseal), which isolates the ambient atmosphere from the reactiveatmosphere. The seal or sealing means may have a composition differentfrom that of the matrix metal.

"Seal Facilitator", as used herein, is a material that facilitatesformation of a seal upon reaction of the matrix metal with the ambientatmosphere and/or the impermeable container and/or the filler materialor preform. The material may be added to the matrix metal, and thepresence of the seal facilitator in the matrix metal may enhance theproperties of the resultant composite body.

"Second or Foreign Metal", as used herein, means any suitable metal,combination of metals, alloys, intermetallic compounds, or sources ofeither, which is, or is desired to be, incorporated into the metalliccomponent of a formed ceramic composite body in lieu of, in addition to,or in combination with unoxidized constituents of the parent metal. Thisdefinition includes intermetallic compounds, alloys, solid solutions orthe like formed between the parent metal and a second metal.

"Second Body" or "Additional Body", as used herein, means another bodywhich is capable of being bonded to a metal matrix composite body by atleast one of a chemical reaction and/or a mechanical or shrink fit. Sucha body includes traditional ceramics such as sintered ceramics, hotpressed ceramics, extruded ceramics, etc., and also, non-traditionalceramic and ceramic composite bodies such as those produced by themethods described in Commonly Owned U.S. Pat. No. 4,713,360, whichissued Dec. 15, 1987, in the names of Marc S. Newkirk et al.; CommonlyOwned U.S. patent application Ser. No. 819,397, filed Jan. 17, 1986, inthe names of Marc S. Newkirk et al., and entitled "Composite CeramicArticles and Methods of Making Same", now allowed; Commonly Owned andCopending U.S. patent application Ser. No. 861,025, filed May 8, 1986,in the names of Marc S. Newkirk et al., and entitled "Shaped CeramicComposites and Methods of Making the Same"; Commonly Owned U.S. patentapplication Ser. No. 152,518, filed on Feb. 5, 1988, in the names ofRobert C. Kantner et al., and entitled "Method For In Situ Tailoring theMetallic Component of Ceramic Articles and Articles Made Thereby", nowallowed; Commonly Owned and Copending U.S. application Ser. No. 137,044,filed Dec. 23, 1987, in the names of T. Dennis Claar et al., andentitled "Process for Preparing Self-Supporting Bodies and Products MadeThereby"; and variations and improvements on these processes containedin other Commonly Owned Allowed and Copending U.S. Applications. For thepurpose of teaching the method of production and characteristics of theceramic and ceramic composite bodies disclosed and claimed in thesecommonly owned applications, the entire disclosures of theabove-mentioned applications are hereby incorporated by reference.Moreover, the second or additional body of the instant invention alsoincludes metal matrix composites and structural bodies of metal such ashigh temperature metals, corrosion resistant metals, erosion resistantmetals, weldable metals, solderable metals, etc. Accordingly, a secondor additional body includes a virtually unlimited number of bodies.

"Second Material", as used herein, refers to a material selected fromthe group consisting of a ceramic matrix body, a ceramic matrixcomposite body, a metal body, and a metal matrix composite body.

"Solid Oxidant" as used herein in conjunction with the formation ofcoatings on a substrate, means an oxidant in which the identified solidis the sole, predominant, or at least a significant oxidizer of, forexample, a parent metal vapor under the conditions of the process.

"Solid Oxidant-Containing Material" as used herein in conjunction withthe formation of coatings on a substrate, means a material whichcontains a solid oxidant. The solid oxidant may comprise substantiallyall of the material or may comprise only a portion of the material. Thesolid oxidant may be substantially homogeneously or heterogeneouslylocated within the material.

"Solid Oxidant Powder" as used herein in conjunction with the formationof coatings on a substrate, means an oxidant in which the identifiedsolid is the sole, predominant, or at least a significant oxidizer of aparent metal powder and/or parent metal vapor and which is located on atleast a portion of a surface of another material (e.g., a solidoxidant-containing material).

"Solid-Phase Oxidant" or "Solid Oxidant", as used herein, means anoxidant in which the identified solid is the sole, predominant or atleast a significant oxidizer of the parent or precursor metal under theconditions of the process. When a solid oxidant is employed inconjunction with the parent metal and a filler, it is usually dispersedthroughout the entire bed of filler or that portion of the bed intowhich the oxidation reaction product will grow, the solid oxidant being,for example, particulates admixed with the filler or coatings on thefiller particles. Any suitable solid oxidant may be thus employedincluding elements, such as boron or carbon, or reducible compounds,such as silicon dioxide or certain borides of lower thermodynamicstability than the boride reaction product of the parent metal. Forexample, when boron or a reducible boride is used as a solid oxidant foran aluminum parent metal, the resulting oxidation reaction productcomprises aluminum boride.

In some instances, the oxidation reaction of the parent metal mayproceed so rapidly with a solid oxidant that the oxidation reactionproduct tends to fuse due to the exothermic nature of the process. Thisoccurrence can degrade the microstructural uniformity of the ceramicbody. This rapid exothermic reaction can be ameliorated by mixing intothe composition relatively inert fillers which absorb the excess heat.An example of such a suitable inert filler is one which is identical, orsubstantially identical, to the intended oxidation reaction product.

"Spontaneous Infiltration", as used herein, means that the infiltrationof matrix metal into the permeable mass of filler or preform occurswithout requirement for the application of pressure or vacuum (whetherexternally applied or internally created).

"Vapor-Phase Oxidant", as used herein, means an oxidant which containsor comprises a particular gas or vapor and further means an oxidant inwhich the identified gas or vapor is the sole, predominant or at least asignificant oxidizer of the parent or precursor metal under theconditions obtained in the oxidizing environment utilized. For example,although the major constituent of air is nitrogen, the oxygen content ofair is the sole oxidizer for the parent metal because oxygen is asignificantly stronger oxidant than nitrogen. Air therefore falls withinthe definition of an "Oxygen-Containing Gas Oxidant" but not within thedefinition of a "Nitrogen-Containing Gas Oxidant" (an example of a"nitrogen-containing gas" oxidant is forming gas, which typicallycontains about 96 volume percent nitrogen and about 4 volume percenthydrogen) as those terms are used herein and in the claims.

"Weight Gain", as used herein, means the percentage weight gain of theingot/filler combination with respect to the weight of the ingot alonebefore initiation of the oxidation reaction. The weight gain cantherefore be calculated by measuring the weight of the ingot/fillerafter growth, subtracting the weight of the ingot/filler before growthdividing by the weight of the ingot before growth and multiplied by 100.

"Wetting Enhancer", as used herein, refers to any material, which whenadded to the matrix metal and/or the filler material or preform,enhances the wetting (e.g., reduces surface tension of molten matrixmetal) of the filler material or preform by the molten matrix metal. Thepresence of the wetting enhancer may also enhance the properties of theresultant metal matrix composite body by, for example, enhancing bondingbetween the matrix metal and the filler material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a blow molding tool whichcan be manufactured in accordance with the present invention;

FIG. 2 is a schematic cross-sectional view of a vacuum forming toolwhich can be made in accordance with the present invention;

FIG. 3 is a schematic cross-sectional view of a compression molding toolwhich can be made in accordance with the present invention;

FIG. 4 is a schematic cross-sectional view of a transfer molding orinjection molding tool which can be made in accordance with the presentinvention;

FIG. 5 is a schematic cross-sectional view of a lay-up tool which can bemade in accordance with the present invention;

FIG. 6 is a schematic cross-sectional view of a vacuum lay-up tool whichcan be made in accordance with the present invention;

FIGS. 7A and 7B are schematic cross-sectional views of the first step inmaking a mold for the formation of a metal matrix composite tool inaccordance with Example 1;

FIGS. 8A and 8B are schematic cross-sectional views of the method formaking a rubber mold which will utilized to make a mold for making thetool in accordance with Example 1;

FIG. 9 is schematic cross-sectional views of rubber mold utilized tomake preforms corresponding the metal matrix composite tool which is tobe formed in accordance with Example 1;

FIG. 10 is a schematic cross-sectional view of an injection molding toolinsert made in accordance with Example 2; and

FIGS. 11A and 11B show how axial deviation is measured on a part madefrom the injection molding tool insert of Example 2, said part beingshown in cross-section in both top view and side view, respectively.

BEST MODES FOR CARRYING OUT THE INVENTION

In accordance with the present invention, there are provided a pluralityof novel methods for forming novel tools from novel tool materials. Ineach of these methods, specific desirable aspects of the formationmethods, as well as advantages attendant the resultant tool material,should become readily apparent.

This application focuses primarily upon tools for use in thermoplasticformation processes, however, it should be noted that tools of similarshape and/or composition and/or nature could be made by substantiallysimilar techniques and used in other plastic formation processesincluding plastic formation of metals, ceramics, glasses, etc. Thus,while specific focus is directed to thermoplastic formation techniques,the scope of the claims appended hereto should not be interpreted asbeing limited only to heated plastic or polymer formation techniques.

In a first preferred embodiment of the invention, a tool for a plasticformation process is manufactured from a metal matrix composite body.The formation process for making the tool can be any suitable metalmatrix composite formation process including, in specific preferredembodiments of the invention, the spontaneous infiltration andself-generated vacuum metal matrix composite formation techniquesdiscussed in the Commonly Owned Patents and Patent Applicationsdiscussed above herein and incorporated by reference herein.

When tools are manufactured by the above-discussed metal matrixcomposite formation techniques, the formed tools will have significantadvantages over tools known in the art. For example, by utilizing theteachings of the above-discussed Commonly Owned Metal Matrix Patents andPatent Applications, tools can be engineered to exhibit a coefficient ofthermal expansion which is compatible with products which are to bemanufactured in, on or from the tool. The matching of the coefficient ofthermal expansion of the tool to the coefficient of thermal expansion ofthe formed product is an important aspect of the invention because itpermits parts having complex shapes to be produced reliably from metalmatrix composite tools. Further, these formed tools can be made to netor near net shape due to the ability to infiltrate a matrix metal into apreshaped mass of filler material or into a preform of filler material.The ability to make net or near net shapes is important because nocomplex machining of, for example, metal parts is required.Additionally, there are shortened tooling lead times required for makingthe tools because of the ability of simple molds to be made from masterparts, the molds thereafter being capable of being filled with a fillermaterial and infiltrated with a matrix metal. Alternatively, molds canbe utilized to form preforms of filler material which are thereaftercoated with barrier materials and the coated preform of filler materialis infiltrated by molten matrix metal.

Still further, the ability to select particular compositions and/orparticle size distributions, etc., of filler materials, enable toolsmade according to the present invention to have, for example, controlledthermal conductivity, controlled wear resistance, high stiffnesscharacteristics, etc. Thus, by choosing a particular composition, sizedistribution, grading, etc., of filler materials, in combination withappropriate choices of matrix metals, metal matrix composite tools canbe manufactured to have properties which are highly desirable for use inthermoplastic forming processes. For example, by causing a tool to havea very high thermal conductivity, the thermal management ofthermoplastically formed bodies can be enhanced. Specifically, fastercycle times for the manufacturing of parts from tools can result fromtools manufactured to have relatively high thermal conductivities.

Still further, by appropriate selection of a combination of fillermaterials and matrix metal, metal matrix composite tools can operate atrelatively high temperatures resulting in the ability to form parts ofeven more desirable properties. Still further, in contrast to, forexample, tooling steels, metal matrix composite tooling materials can bemade to be about 60 percent lighter than typical tooling steels whilemaintaining stiffnesses at least as great as that of tooling steels, andin some cases exhibit stiffness much greater than stiffnesses of toolingsteels.

In another preferred embodiment of the invention, specific cooling orheating channels can be designed into specific desirable areas of toolmaterials. In this regard, in some cases, when a thermoplastic materialis plastically deformed, either by injection molding, compressionmolding, etc., it may be desirable for the tool material to be locallyheated or cooled in certain areas to enhance, for example, the surfacefinish, mechanical properties, etc., of a formed part. In some cases, itmay be desirable for the cooling and/or heating channels to be formed ofa material of different composition than the metal matrix compositebody. In this instance, a macrocomposite body can be formed. Themacrocomposite body can be formed in accordance with the teachings inthe above-discussed Commonly Owned Metal Matrix Composite Patent andPatent Applications.

In another preferred embodiment of the invention, tooling materials canbe made from ceramic matrix composite bodies. Specifically, theabove-discussed Commonly Owned Ceramic Matrix Patents and PatentApplications can also be utilized to manufacture tooling materials. Manyof the above-discussed advantages attendant to metal matrix compositebodies also are applicable in tooling materials made from ceramic matrixcomposite bodies. Specifically, specific combinations of fillermaterials, parent metals (and thus, the resulting oxidation reactionproduct) can be selected in an appropriate manner to achieve, forexample, desirable thermal expansion coefficient, wear resistance,stiffness, strength, high temperature strength, and thermalconductivity. Moreover, the ability to make net or near net shapedceramic matrix composite tools is also an advantage of these formationmethods.

Still further, macrocomposite bodies can be formed in ceramic matrixcomposite bodies as well. In this embodiment, cooling and/or heatingchannels may also be incorporated into the formed tool, thereby forminga macrocomposite body.

In a still further preferred embodiment of the invention, surfacecoatings may be placed onto at least a portion of a surface of asubstrate material to enhance the ability of the substrate material tofunction as a tool. For example, graphite materials have historicallybeen utilized in some tooling applications. However, while graphite hassome desirable tooling aspects (e.g., good thermal conductivity andmachinability), many forms of graphite are relatively prone to rapidwear and physical damage from, for example, normal handling procedures.Additionally, some graphite materials are too porous to function as toolmaterials (e.g., in vacuum formation processes hermaticity of the toolis essential). However, if these types of materials could be coated witha material which enhances, for example, the wear resistance of the tool,the hermiticity of the tool, etc., then the tool may be made to besuitable for use as a tool or may provide for enhanced performance of atool. In a preferred embodiment of the invention, a graphite toolsubstrate can be coated with a reaction product coating which may beformed from a reaction between a vapor-phase parent metal and a solidoxidant, said solid oxidant being capable of being separately coatedonto a surface of a substrate or contained within at least a portion ofthe substrate. The manner for forming such reaction product coatings isdiscussed in the above-mentioned Copending and Commonly Owned CeramicMatrix Patents and Patent Applications.

Moreover, in another preferred embodiment, a ceramic matrix compositematerial can be formed as a surface coating on at least a portion of asubstrate material. In this embodiment, a coating can be made in amanner similar to that manner discussed immediately above herein,however, in addition, a filler material may be located on at least aportion of a substrate material. Moreover, a powdered parent metaland/or vapor-phase parent metal and/or solid oxidant can be conjoinedunder the process conditions to result in a coating on at least aportion of a surface of a substrate material.

In each of the above-discussed preferred embodiments relating to theformation of coatings on a substrate material, the resultant coating canbe formed so that it enhances the wear properties, as well as thehermeticity, of the underlying substrate material. However, it should beunderstood that these coatings may also enhance the performance of theabove-discussed metal matrix composite tools as well as theabove-discussed ceramic matrix composite tools.

Moreover, the specific technique for coating surfaces of a substratematerial should not be limited to the above-discussed Commonly Owned andCopending Ceramic Matrix Patent and Patent Applications. Specifically,it is possible that desirable coatings on substrate materials can beachieved by various techniques including the deposition of overlaycoatings by, for example, chemical vapor deposition, hot spraying,physical vapor deposition, etc. Moreover, a number of hot sprayingtechniques also exist for the placement of overlay coatings on asubstrate material. Three commonly used hot spraying techniques includeflame spraying, plasma spraying and detonation coating. Still further,conversion coating techniques can also be utilized to form desirablecoatings on the surface of substrate materials which are to be utilizedas tools. Pack cementation and slurry cementation are commonly knownexamples of methods for placing coatings on substrate materials. Theprecise combination of composition, thickness, coefficient of thermalexpansion, thermal properties, etc., of these coatings need to beselected based upon the particular intended application of the tool.

In each of the above-discussed preferred embodiments, it may bedesirable to design a surface of a tool so that a desirable surfacetexture on a formed part will result. For example, in certainapplications such as plastic part formation operations, it may bedesirable for the formed part to have a leather-like texture. In thiscase, matrix metal from metal matrix composite tools or parent metalfrom ceramic matrix composite tools could be selectively removed from atleast a portion of a surface of a tool so that the filler material(e.g., coarse particles) could protrude from at least a portion of thesurface and thus create their own unique surface texture in parts formedtherefrom. This technique could be utilized in selected regions of atool or over the entire tool to obtain a desirable surface texture.

Moreover, in each of the above-discussed preferred embodiments,controlling the laminar flow of an injected plastic material into a moldor tool may permit a more rapid filling of a mold or tool cavityrelative to a mold or tool cavity which does not have such interferencewith laminar flow. For example, in a specifically preferred embodimentof the invention, surface bumps (e.g., a few microns high) in spurs orgates (such as those spurs or gates which are normal pathways in toolingthrough which thermoplastic materials are passed on their way into amold cavity) may result in the introduction of a turbulence where aninjected plastic material contacts the wall or sprue of such gates. Theintroduction of turbulence will have the effect of reducing drag on thethermoplastic material which is injected, thus reducing laminar adhesionand enhancing the manufacture of the parts.

FIGS. 1-6 of the application show various exemplary uses for tools. Ineach of the figures, similar reference numerals have been used whereverpossible when reference is made to like portions in each figure. In eachof the figures, the numeral 21 references a material which is to bedeformed (e.g., a plastic or a polymer); the numeral 22 references atool; and the numeral 23 references a cavity into which thethermoplastic material is to be deformed.

With specific reference to FIG. 1, a cross-section of a blow moldingtool is disclosed. In this embodiment, the tool halves 22 clamp aroundthe material 21 which is to be deformed and a positive pressure isapplied to an interior portion of the material 21 causing it to fill thecavity 23, thereby conforming to the shape of the cavity 23. The mold isthereafter opened and the formed part is removed.

FIG. 2 shows a schematic cross-sectional view of a vacuum forming tool.In this figure, a vacuum is created, by any appropriate means, withinthe cavity 23. The thermoplastically deformable material 21 then assumesthe shape of the cavity 23 within the tool 22.

A compression molding tool is shown in schematic cross-section in FIG.3. In this tool 22, cavities 23 are formed into which thethermoplastically deformable material 21 is caused to flow when the toolportions 22 and 22A are pressed together.

FIG. 4 shows a schematic cross-sectional view of a transfer molding orinjection molding tool. In this embodiment, a thermoplasticallydeformable material 21 is pressured by an appropriate force "A" to causeit flow into the cavity portion 23 created by the tool parts 22 and 22A.The resultant body accordingly conforms to the shape of the cavities 23.

A typical lay-up tool is shown in cross-section in FIG. 5. In thisembodiment, a material 21, which may or may not be thermoplasticallydeformable, is placed into contact with the tool 22 as shown. Specificmaterials for use as the material 21 include various films or filmlaminates such as "prepregs" (e.g., combinations of various fillermaterials and organic resin binders). The tool 22, containing thematerial coating 21, may thereafter be placed into, for example, anautoclave causing the, for example, prepreg material to solidify andtake the shape of the tool.

FIG. 6 shows in schematic cross-sectional view the vacuum lay-up toolwhich can utilize materials of the present invention. In thisembodiment, materials such as those discussed immediately above (i.e.,prepregs, etc.) referenced here by the numerals 24 and 25, can be placedinto contact with the surface of the tool 22 and covered by a vacuum bag27 thereby forming a cavity 26 between the materials 24, 25, the vacuumbag 27, and the tool 22. A vacuum is then applied inside the vacuum bag27 so as to cause the vacuum bag 27 to substantially eliminate thecavity 26 (i.e., the vacuum bag 27 is caused to contact a substantialportion of the surface of the materials 24 and 25. Additionally,temperature can be applied simultaneously with the vacuum to cause thematerials 24 and 25 to solidify to form a part conforming to the tool22.

In each of exemplary embodiments contained in FIGS. 1-6, the toolmaterial 22 is made of materials according to the present invention.Accordingly, the tool materials exhibit enhanced performance in areassuch as better wear resistance, better thermal conductivity, rapidproduction times, etc.

It is noted that the use of cooling channels and/or protuberances arenot expressly disclosed in any of FIGS. 1-6. However, for example, inreference to FIG. 2, a cooling channel could be located within the tool22 adjacent to cavity portion 23. Such cooling channel could result inmore rapid solidification of a thermoplastically deformed materialrelative to a similar tool which could not include a cooling channel.

Moreover, in reference to FIG. 4, a means to interfere with the laminarflow of the thermoplastically deformable material 21 could be locatedsomewhere within the channel through which thermoplastically deformablematerial 21 flows (e.g., either in throat of the tool or in the internalfeed cavities within the tool). The placement of these laminar controlflow means as well as the shape (e.g., cross-section) depends upon thetype of thermoplastic material utilized to form a part as well as therate at which deformation occurs.

The following contain Examples of the present invention, however, theExamples, as well as the above-discussed preferred embodiments, shouldnot be construed as limiting the scope of the invention as defined bythe attached claims.

Example 1

This Example demonstrates a method of manufacturing metal matrixcomposite lens tools. Specifically, a plaster molding mixture comprisingabout 60% by weight USG-1 Industrial Plaster (Samuel H. French,Philadelphia, Pa.) and 40% by weight room temperature tap water wasprepared. As shown in FIG. 7A, a lens model 2 was placed in the bottomof a container 1. A wax layer 3 was built up around the lens model to alevel substantially flush with the top of the lens model 2. The plastermixture 4 was then poured into the container 1 and onto the lens model 2surrounded by the wax layer 3. The plaster mixture 4 was allowed to curein the container 1 for at least 2 hours. The plaster/wax/lens modelassembly was removed from the container, inverted, and repositioned inthe container 1 such that the plaster layer 4 contacted the bottom ofthe container 1. As shown in FIG. 7B, four holes 5, each about 3/4 inch(1.9 cm) in diameter, were drilled through the wax layer 3 and just intothe plaster layer 4 to make indentations at the corners. Theindentations were then coated with a thin layer of COLLOID 581-Bdefoamer (Colloids, Inc., Newark, N.J.) to act as a releasing agent. Afresh plaster molding mixture 6, having a composition as describedabove, was then poured into the container 1 and onto the invertedplaster/wax/lens model assembly. The plaster mixture 6 was allowed tocure in the container 1 for at least 2 hours. The plaster parts 4 and 6were then removed from the container 1, separated from the wax layer 3and lens model 2, and placed into an air circulating oven at about 32°C. and allowed to dry about 24 hours.

As shown in FIG. 8A, the male plaster lens tool model 6, having aserrated cross-section 8 and alignment pins 7, was placed within acontainer 2 with the flat side of the plaster lens tool model 6contacting the bottom surface of the container 2 and the serratedcross-section 8 and alignment pins 7 facing up. A rubber moldingcompound (GI-1000, Plastic Tooling Supply Co., Easton, Pa., about 1 partby weight activator and about 10 parts by weight rubber base) was pouredinto the container 2 and onto the male plaster lens tool model 6. Therubber mold 11 was allowed to cure at room temperature for about 16hours. The rubber mold 11 was then carefully removed from around themale plaster lens tool model 6 and cleaned with hot water and liquidsoap.

As shown in FIG. 8B, the female plaster lens tool model 4, having aserrated cross-section 9 and alignment holes 10, was placed within acontainer 2 with the flat side of the plaster lens tool model 4contacting the bottom surface of the container 2 and the serratedcross-section 9 and alignment holes 10 facing up. A rubber moldingcompound 12, having a composition as described above, was poured intothe container 2 and onto the female plaster lens tool model 4. Therubber mold 12 was allowed to cure at room temperature for about 16hours. The rubber mold 12 was then carefully removed from around thefemale plaster lens tool model 4 and cleaned with hot water and liquidsoap.

An aqueous solution of BLUONIC® A colloidal alumina (West BondCorporation, Wilmington, Del.) weighing about 238 grams was diluted withabout 462 grams of deionized water and placed into a plastic jar (VWRScientific, Bridgeport, N.J). About 2000 grams of 500 grit 39 CRYSTOLON®green silicon carbide particulate (Norton Company, Worcester, Mass.) andabout 2 milliliters of COLLOID 581-B defoamer (Colloids, Inc., Newark,N.J.) were added to the jar to prepare a slurry for sediment casting.The slurry was then roll mixed for about 20 hours on a jar mill. Therubber mold 11, having an internal cavity measuring about 9 inches (23cm) by about 7 inches (18 cm) and about 11/4 inch (3.2 cm) deep, wasplaced onto a flat rigid aluminum plate. The mold/plate assembly wasthen placed onto a level vibrating table. The vibrating table was turnedon, the slurry was removed from the jar mill and about 97% of the slurrywas poured into the mold in a smooth and continuous manner. The mold andits contents were then subjected to vibration for about 1 hour tocondense the slurry into a preform, with excess surface liquid beingremoved with a sponge. The vibrating table was turned off and themold/plate/preform assembly was placed into a freezer. After residualwater in the preform was substantially completely frozen, then themold/plate/preform assembly was removed from the freezer and the frozensediment cast preform 16, having dimensions of about 9 inches (23 cm) byabout 7 inches (18 cm) and about 3/4 inch (1.9 cm) thick, was removedfrom the mold.

An about 1 inch layer of 500 grit 38 ALUNDUM® alumina (Norton Company)was poured into a graphite boat. The preform 16 was then placed onto the1 inch (2.5 cm) thick layer of 500 grit 38 ALUNDUM® alumina with theserrated cross-section 8 and alignment pins 7 contacting the 500 grit 38ALUNDUM® alumina. Additional support for the preform was supplied bysurrounding it with 24 grit 38 ALUNDUM® alumina (Norton Company), withcare being taken not to allow the 24 grit 38 ALUNDUM® alumina to touchthe serrated cross-section 8 and alignment pins 7. The graphite boat andits contents were placed into a controlled atmosphere furnace at aboutroom temperature. A nitrogen gas flow rate of about 15 liters per minutewas established within the furnace. The temperature in the furnace wasthen increased to about 85° C. in about 1/2 hour. After maintaining atemperature of about 85° C. for about 12 hours, the temperature in thefurnace was increased to about 1050° C. at a rate of 100° C. per hour.After maintaining a temperature of about 1050° C. for about 2 hours, thetemperature in the furnace was decreased to about room temperature at arate of about 200° C. per hour. The graphite boat and its contents werethen removed from the furnace. The preform 16 was removed from thegraphite boat, and loose 38 ALUNDUM® alumina was removed from thepreform 16.

A preform barrier coating was prepared by mixing about 60% by volume ofDAG® 154 colloidal graphite (Acheson Colloids Co., Port Huron, Mich.)with about 40% by volume denatured ethanol. The barrier coating was thensprayed onto five sides of the preform using a touch-up gun. The bottomflat surface of the preform 19 was not coated. The barrier was allowedto air dry at room temperature prior to again spray coating. Thisprocedure was repeated 11 times, so that the preform had 12 coats ofbarrier. The now coated preform 16 was placed into a controlledatmosphere furnace and a nitrogen gas flow rate of about 15 liters perminute was established. The temperature in the furnace was raised fromabout room temperature to about 800° C. at a rate of about 200° C. perhour. After maintaining a temperature of about 800° C. for about 1 hour,the temperature in the furnace was decreased to about room temperatureat a rate of about 200° C. per hour. The preform 16 was removed from thefurnace and it was noted that the graphite coating 17 had set on thepreform 16.

As shown in FIG. 9, a graphite foil box 13, having dimensions of about101/2 inches (27 cm) by about 91/2 inches (24 cm) and about 11/2 inch(3.8 cm) high, was constructed from a single sheet of GRAFOIL® graphitefoil (Union Carbide Co., Danbury, Conn.) measuring about 0.015 inch(0.04 cm) thick. Strategically placed staples helped to reinforce thefolds in the graphite foil box 13. The graphite foil box 13 was placedwithin a graphite boat 18 having inside dimensions substantially thesame as the outside dimensions of the graphite foil box 13. A matrixmetal ingot weighing about 2915 grams and comprised by weight of about15% silicon, about 5% magnesium and the balance aluminum, was cut intotwo strips. The matrix metal ingot strips 15 were then placed in thebottom and opposite end of the graphite foil box 13. The preform 16 wasthen placed on top of the matrix metal ingot strips 15 in a manner suchthat the strips were on an outer edge of the preform 16 and the serratedcross-section 8 and alignment pins 7 were on the top side of the lay-up.A graphite foil box cover 14 having inner dimensions substantially thesame as the outer dimensions of the graphite boat 18 was prepared in amanner substantially the same as described above. The graphite foil boxcover 14 was inverted and placed over the graphite boat 18, covering theboat/lay-up assembly.

A temperature of 125° C. was established within a resistance heatedcontrolled atmosphere furnace, then the graphite boat 18 and itscontents were placed in the furnace. The furnace was sealed, evacuatedto about 30 inches of mercury vacuum, and backfilled with nitrogen gasto about atmospheric pressure. A nitrogen gas flow rate of about 15liters per minute was established within the furnace. The temperature inthe furnace was increased to about 785° C. at a rate of about 200° C.per hour. After maintaining a temperature of about 785° C. for about 20hours, the furnace was opened and the graphite boat 18 and its contentswere removed and placed on a ceramic plate. The graphite foil box cover14 was removed and the pool of molten matrix metal surrounding the metalmatrix composite body 16 was covered with an about 2 inch thick layer ofFIBERFRAX® ceramic insulation material (Carborundum Company, NiagaraFalls, N.Y.). The sides of the graphite boat 18 were also wrapped withFIBERFRAX® ceramic insulation material; however, the metal matrixcomposite body comprising the infiltrated preform comprising theinfiltrated preform was not covered. When the assembly reached roomtemperature, the metal matrix composite body 16 comprising theinfiltrated preform was removed from the graphite boat 18, placed in avice, and residual matrix metal was removed from the metal matrixcomposite body male tool with light hammer blows. Thus forming the maleportion of a metal matrix composite lens tool.

The female portion of the lens tool was produced in substantially thesame manner as described above, except that the rubber mold 12 shown inFIG. 8B was used. Moreover, the preform barrier coating was prepared bymixing 50% by volume of DAG® 154 colloidal graphite (Acheson Colloids,Port Huron, Mich.) with about 50% by volume denatured ethanol. Thebarrier coating was then applied to five sides of the preform using anair brush. As with the male portion of the lens tool, the bottom flatsurface of the preform for the female portion of the lens tool was notcoated. The barrier was allowed to air dry and the procedure wasrepeated about 20 times. Finally, a single preform barrier coating wasapplied to the five sides of the female preform with a foam brush.

The lay-up and method for forming the female portion of the lens toolswere substantially the same as the lay-up and method for forming themale portion of the lens tool.

Example 2

The following Example demonstrates a method for manufacturing aninjection molding tool insert for plastics from a metal matrixcomposite. Specifically, the following Example demonstrates theformation of an injection molding tool insert for plastics from a metalmatrix composite and a substantially identical tool insert from P-20tool steel. A direct comparison was made between certain operationalcharacteristics of the injection molding tool inserts made from the twomaterials as well as differences between the plastic bodies madetherefrom.

FIG. 10 is a cross-sectional view of an injection molding tool insert 20comprised of a cavity section 21 and a core section 22. The cavitysection 21 included an injection gate 29, a coolant channel 26connecting a coolant inlet 23 to a coolant outlet 27. Core section 22further comprised a coolant channel 25 connecting a coolant inlet 24 toa coolant outlet 28. During the operation of the injection molding tool,core section 22 and cavity section 21 of the injection molding toolinsert 20 were contacted as depicted in FIG. 10 to form a plastic partcavity 30 into which molten plastic was injected. Simultaneously, acoolant was passed through cooling channels 25 and 26.

Injection molding tool insert 20 comprised of a metal matrix compositewas formed by first forming core section blanks and cavity sectionblanks by a method similar to that described in Example 1, with thecoolout channel 25 and coolout channel 26 of the respective core sectionand cavity section being formed in situ. Specifically, a sedimentcasting mixture was made substantially according to the methods ofExample 1, except that the 500 grit (average particle diameter of about17 microns) 39 CRYSTOLON® green silicon carbide particulate (Norton Co.,Worcester, Mass.) was substituted with a silicon carbide mixturecomprised by weight of about 70 percent 220 grit (average particlediameter of about 66 microns) 39 CRYSTOLON® green silicon carbideparticulate and 30 percent 500 grit (average particle diameter of about17 microns) 39 CRYSTOLON® green silicon carbide particulate (both fromNorton Co., Worcester, Mass.). Furthermore, the sediment casting of thesilicon carbide preform was done in a polymethyl methacrylate mold,commonly known as Plexiglass®, measuring about 3.5 inches (88.9 mm)square by about 4 inches (102 mm) deep and around a wax mandrel to formthe coolant channels. After the sediment cast preforms containing theembedded wax mandrel comprised of 0.375 inch (9.5 mm) diameter Red-C wax(Yate Wax) were removed from the freezer, the frozen sediment castpreforms having dimensions of about 3 inches (76 mm) square by about 3inches (76 mm) thick were removed from the polymethyl methacrylatemolds. The preforms were then processed substantially according to themethod of Example 1 to remove the wax mandrel defining the internalchannel, except that the furnace and its contents were heated from aboutroom temperature to about 85° C. in about an hour, maintained at 85° C.for about 12 hours, heated from about 85° C. to about 500° C. at about100° C. per hour, maintained at about 500° C. for about 4 hours, heatedfrom about 500° C. to about 1200° C. at about 150° C. per hour. Afterabout 2 hours at about 1200° C., the energy to the furnace wasinterrupted and the furnace and its contents were allowed to coolnaturally to about room temperature. At about room temperature, thepreform was removed from the furnace and it was noted that the waxmandrel embedded within the preforms had melted to form channels in thepreform.

The channels within the preform were then filled with a mixturecomprised of DYLON® Grade CW colloidal graphite (Dylon Industries Inc.,Berea, Ohio) and KS 44 graphite (Lonza, Fairlawn, N.J.). The preform wasthen placed in the bottom of a graphite boat made from Grade ATJgraphite (Union Carbide Corporation, Carbon Products Division,Cleveland, Ohio). The graphite boat had inner dimensions measuring about7 inches (178 mm) square and a depth of about 5 inches (127 mm). Afterthe preform had been centered within the graphite boat, NYAD® FP coarsegrade wollastonite (NYCO Minerals, Inc., Willsboro, N.J.) was pouredinto the space between the inner walls of the graphite boat and theouter perimeter of the preform to a depth of about 2.5 inches (64 mm). Amixture comprised by weight of about 2 percent F-69 glass frit (FusionCeramics Inc., Carrollton, Ohio) and about 98 percent 90 grit (averageparticle diameter of about 216 microns) electronic grade 38 ALUNDUM®alumina (Norton Co., Worcester, Mass.) was then poured to the height ofthe preform and leveled with the surface of the preform. A piece ofgraphite foil having slits corresponding in shape to an "X" and to thesize of the surface of the preform was then placed in the graphite boatto cover the preform and materials surrounding the preform. A sufficientamount of about -50 mesh (particle diameter less than about 300 microns)magnesium powder was then placed along the slits forming the "X" withinthe graphite foil. A matrix metal ingot weighing about 1598 grams andhaving a composition comprised by weight of about 12.5 percent silicon,3 percent magnesium and the balance aluminum was then placed on thegraphite foil and on top of the -50 mesh magnesium powder. Additionalmaterial comprised of F-69 grit and 90 grit (average particle diameterof about 216 microns) electronic grade 30 ALUNDUM® alumina was thenplaced in the space between the matrix metal ingot and the graphite boatwalls, so as to completely cover the matrix metal ingot, thereby forminga lay-up.

The lay-up was then placed into a controlled atmosphere furnace and thefurnace door was closed. The furnace and its contents were thenevacuated to about 30 inches (762 mm) of mercury vacuum, backfilled withnitrogen to about atmospheric pressure, again evacuated to about 30inches (762 mm) of mercury vacuum and finally backfilled with nitrogengas to a flow rate of about 4 liters per minute at atmospheric pressure.The furnace and its contents were then heated from about roomtemperature to about 225° C. at about 100° C. per hour, held at about225° C. for about 2 hours, heated from about 225° C. to about 525° C. atabout 90° C. per hour, held at about 525° C. for about 4 hours, thenheated from about 525° C. to about 825° C. at about 150° C. per hour.After about 20 hours at about 825° C., the furnace and its contents wereallowed to cool to about room temperature. At about room temperature,the lay-up was disassembled and it was noted that the preform had beeninfiltrated by the matrix metal to form a metal matrix composite core orcavity blank. The above procedure was repeated to form additional coreblanks and cavity blanks.

The core and cavity blanks were then machined using conventional diamondmachining in combination with RAM EDM machining to form a core sectionand a cavity section as depicted in FIG. 10. Specifically, the coresection 22 measured about 3.5 inches (81 mm) square, about 1.25 inches(32 mm) thick and had a section that extended about 0.27 inch (6.9 mm)beyond the center line of the injection molding tool insert 20.Furthermore, the coolant channels 25 and 26 had a diameter about 0.375inch (9.5 mm). The cavity section 21 measured substantially the same asthat of the core section 22, except that instead of having a portionextending beyond the surface, it had a recess cavity measuring about0.377 inch (9.6 mm) deep.

Injection Molding Comparison

Once the core and cavity sections comprising the metal matrix compositeinjection molding tool insert were prepared as discussed above, similarcore and cavity sections made from P-20 tool steel were also made.Specifically, core and cavity portions were machined in a standardmanner from P-20 tool steel to form core and cavity sections whichsubstantially exactly replicated the size and shape of the metal matrixcomposite injection molding tool insert.

Each of the core and cavity sections manufactured from the metal matrixcomposite material and the P-20 tool steel were placed in a standardtooling mold base and functioned as part-forming inserts therein.Specifically, when plastic was injected into the gates 29 from a moldingmachine (not shown in drawings), the plastic simultaneously filled eachof the cavities 30 contained in each of the metal matrix composite toolinsert and the P-20 tool steel insert. The molding machine whichcommunicated with the tool inserts was a Toshiba 250 ton moldingmachine. Four different plastics were injection molded into each of thetool inserts under different sets of processing parameters. The toolinserts were arranged in the mold base so that plastic could besimultaneously injected into each tool insert so that each tool insertwas exposed to substantially identical processing conditions. Differentcoolant temperatures were utilized along with different cycle times.Temperature measurements on the formed pieces and on the surface of eachof the mold inserts were made when the plastic pieces were removed fromthe mold inserts. Specifically, Tables I-IV set forth the material whichwas injection molded ("Material"), the temperature of the material whenit was injection molded ("Melt temp."), the pressure exerted upon thematerial to cause it to be injected into the mold ("Screw inj. press."),and the amount of time required to fill the cavities in each of the toolinserts ("Fill time"). In addition, the Tables show in vertical columnsthe temperature of the coolant injected into the cooling channels ineach of the molds ("Coolant Temp"), the amount of time between injectingmaterial into the mold and opening the mold to eject the formed part("Cycle Time"), the temperature of the formed part when it was removedfrom the mold ("Part Temp.") and the temperature of the surface of themold when the part was removed from the mold ("Mold Surface Temp").

The columns entitled "Part Temp" and "Mold Surface Temp"set forth ineach of Tables I-IV show that the metal matrix composite tool insert wassuperior to the P-20 tool steel insert in thermal properties.Particularly, both the temperature of the formed part and the surfacetemperature of the tool insert were consistently lower in the metalmatrix composite tool insert in comparison to the P-20 tool steelinsert. The temperature differential is significant because the faster amold and injected part can cool, the shorter the cycle time betweenforming parts. Accordingly, mold inserts comprising a metal matrixcomposite can decrease the cycle time, thus increasing productionefficiency.

FIGS. 11A and 11B between the dotted lines and the solid lines). It isevident from Tables I-IV that warpage in the parts formed from the metalmatrix composite tool inserts was less than warpage in the parts formedfrom the P-20 tool steel inserts.

In addition, after numerous cycles, no wear of the surfaces of the MMCtool insert material was evident. This was true even though injectionpressures ranged between about 4000-8000 psi (28 MPa-55 MPa).

                                      TABLE I                                     __________________________________________________________________________              Material:           BASF 30% talc filled polyacetal                           Melt temp.:         199° C.                                            Screw inj. press.:  407 kg                                                    Fill time.:         0.7 seconds                                     __________________________________________________________________________    Coolant    Cycle                                                                             Part                                                                              Mold Surface                                                                         Axial Deviation                                           Temp.                                                                              Time                                                                              Temp.                                                                             Temp.  Side 1                                                                              Side 2                                                                              Side 3                                                                              Side 4                                                                              Top                               (°C.)                                                                       (sec.)                                                                            (°C.)                                                                      (°C.)                                                                         (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                     __________________________________________________________________________    P-20 Steel                                                                          32   12  91  77     0.018/0.457                                                                         0.010/0.254                                                                         0.011/0.279                                                                         0.011/0.279                                                                         0.006/0.152                 MMC   32   12  76  38     0.010/0.254                                                                         0.007/0.178                                                                         0.007/0.178                                                                         0.007/0.178                                                                         0.007/0.178                 P-20 Steel                                                                          32   17  69  56     0.015/0.381                                                                         0.008/0.203                                                                         0.007/0.178                                                                         0.008/0.203                                                                         0.006/0.152                 MMC   32   17  55  37     0.008/0.203                                                                         0.005/0.127                                                                         0.005/0.127                                                                         0.005/0.127                                                                         0.006/0.152                 P-20 Steel                                                                          60   12  102 79     0.018/0.457                                                                         0.013/0.330                                                                         0.010/0.254                                                                         0.010/0.254                                                                         0.010/0.254                 MMC   60   12  91  54     0.010/0.254                                                                         0.006/0.152                                                                         0.007/0.178                                                                         0.006/0.152                                                                         0.008/0.457                 P-20 Steel                                                                          60   17  86  82     0.015/0.381                                                                         0.008/0.203                                                                         0.010/0.254                                                                         0.009/0.229                                                                         0.007/0.178                 MMC   60   17  75  53     0.008/0.203                                                                         0.005/0.127                                                                         0.004/0.102                                                                         0.005/0.127                                                                         0.005/0.127                 __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________              Material:         Himont SA747 clarified polypropylene                        Melt temp.:       213° C.                                              Screw inj. press.:                                                                              407 kg                                                      Fill time.:       0.37 seconds                                      __________________________________________________________________________    Coolant    Cycle                                                                             Part                                                                              Mold Surface                                                                         Axial Deviation                                           Temp.                                                                              Time                                                                              Temp.                                                                             Temp.  Side 1                                                                              Side 2                                                                              Side 3                                                                              Side 4                                                                              Top                               (°C.)                                                                       (sec.)                                                                            (°C.)                                                                      (°C.)                                                                         (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                     __________________________________________________________________________    P-20 Steel                                                                          32   12  100 41     0.010/0.254                                                                         0.008/0.203                                                                         0.010/0.254                                                                         0.009/0.229                                                                         0.014/0.356                 MMC   32   12  91  34     0.006/0.152                                                                         0.005/0.127                                                                         0.003/0.076                                                                         0.004/0.102                                                                         0.006/0.152                 P-20 Steel                                                                          32   17  71  39     0.007/0.178                                                                         0.007/0.178                                                                         0.009/0.229                                                                         0.010/0.254                                                                         0.011/0.279                 MMC   32   17  63  32     0.005/0.127                                                                         0.003/0.076                                                                         0.005/0.127                                                                         0.007/0.178                                                                         0.007/0.178                 P-20 Steel                                                                          60   17  93  79     0.005/0.127                                                                         0.007/0.178                                                                         0.008/0.203                                                                         0.008/0.203                                                                         0.003/0.076                 MMC   60   17  86  51     0.003/0.076                                                                         0.003/0.076                                                                         0.004/0.102                                                                         0.004/0.102                                                                         0.005/0.127                 P-20 Steel                                                                          60   22  80  77     0.007/0.178                                                                         0.009/0.229                                                                         0.007/0.178                                                                         0.009/0.229                                                                         0.005/0.127                 MMC   60   22  74  51     0.005/0.127                                                                         0.005/0.127                                                                         0.005/0.127                                                                         0.005/0.127                                                                         0.008/0.203                 __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________                 Material:            Fina polystyrene                                         Melt temp.:          212° C.                                           Screw inj. press.:   407 kg                                                   Fill time.:          0.5 seconds                                 __________________________________________________________________________    Coolant    Cycle                                                                             Part                                                                              Mold Surface                                                                         Axial Deviation                                           Temp.                                                                              Time                                                                              Temp.                                                                             Temp.  Side 1                                                                              Side 2                                                                              Side 3                                                                              Side 4                                                                              Top                               (°C.)                                                                       (sec.)                                                                            (°C.)                                                                      (°C.)                                                                         (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                     __________________________________________________________________________    P-20 Steel                                                                          32   12  74  39     0.004/0.102                                                                         0.003/0.076                                                                         0.004/0.102                                                                         0.003/0.076                                                                         0.002/0.051                 MMC   32   12  64  33     0.002/0.051                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.000/0.000                 P-20 Steel                                                                          32   17  55  46     0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                 MMC   32   17  46  33     0.001/0.025                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.000/0.000                 P-20 Steel                                                                          60   17  72  71     0.003/0.076                                                                         0.003/0.076                                                                         0.003/0.076                                                                         0.003/0.076                                                                         0.001/0.025                 MMC   60   17  67  50     0.002/0.051                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.001/0.025                                                                         0.001/0.025                 P-20 Steel                                                                          60   22  66  66     0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                 MMC   60   22  60  50     0.000/0.000                                                                         0.001/0.025                                                                         0.000/0.000                                                                         0.001/0.025                                                                         0.002/0.051                 __________________________________________________________________________

                                      TABLE IV                                    __________________________________________________________________________              Material:           Mobay FCR polycrabonate                                   Melt temp.:         274° C.                                            Screw inj. press.:  679 kg                                                    Fill time.:         0.65 seconds                                    __________________________________________________________________________    Coolant    Cycle                                                                             Part                                                                              Mold Surface                                                                         Axial Deviation                                           Temp.                                                                              Time                                                                              Temp.                                                                             Temp.  Side 1                                                                              Side 2                                                                              Side 3                                                                              Side 4                                                                              Top                               (°C.)                                                                       (sec.)                                                                            (°C.)                                                                      (°C.)                                                                         (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                                                                             (in/mm)                     __________________________________________________________________________    P-20 Steel                                                                          32   12  76  49     0.005/0.127                                                                         0.003/0.076                                                                         0.004/0,102                                                                         0.003/0.076                                                                         0.005/0.127                 MMC   32   12  66  35     0.003/0.076                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.001/0.025                                                                         0.002/0.051                 P-20 Steel                                                                          32   17  55  49     0.003/0.076                                                                         0.004/0.102                                                                         0.003/0.076                                                                         0.003/0.076                                                                         0.004/0.102                 MMC   32   17  46  35     0.002/0.051                                                                         0.002/0.051                                                                         0.001/0.025                                                                         0.002/0.051                                                                         0.002/0.051                 P-20 Steel                                                                          60   17  95  93     0.004/0.102                                                                         0.003/0.076                                                                         0.004/0.102                                                                         0.004/0.102                                                                         0.004/0.102                 MMC   60   17  84  53     0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.002/0.051                                                                         0.003/0.076                 P-20 Steel                                                                          60   22  76  93     0.004/0.102                                                                         0.004/0.102                                                                         0.004/0.102                                                                         0.004/0.102                                                                         0.004/0.102                 MMC   60   22  67  53     0.002/0.051                                                                         0.002/0.051                                                                         0.001/0.025                                                                         0.002/0.051                                                                         0.003/0.076                 __________________________________________________________________________

What is claimed is:
 1. A metal matrix composite injection molding toolfor plastic materials, said tool comprising:a first metal matrixcomposite portion having therethrough at least one of a sprue or a gateproviding a means for communication between a region external to saidtool and at least one internal cavity for forming said plasticmaterials, wherein at least one surface defining said at least one of agate or a sprue comprises protuberances, wherein said protuberancesintroduce turbulence into said plastic material during flow of saidplastic material in or through said gate or sprue; at least oneadditional metal matrix composite portion coupling in a complementarymanner with said first portion to define further said at least oneinternal cavity.
 2. The tool of claim 1, further comprising at least oneheating or cooling channel located within at least one of said firstmetal matrix composite portion and said at least one additional portion,wherein said at least one heating or cooling channel maximizes at leastone of the production of parts and the mechanical properties of theparts produced in said tool.
 3. The metal matrix composite injectionmolding tool of claim 1, wherein at least one of said first metal matrixcomposite portion and said at least one additional metal matrixcomposite portion comprises an aluminum matrix metal and a siliconcarbide filler material.
 4. The metal matrix composite injection moldingtool of claim 1, wherein at least one of said first metal matrixcomposite portion and said at least one additional metal matrixcomposite portion comprises at least one matrix selected from the groupconsisting of aluminum, bronze, and cast iron and at least one filler isselected from the group consisting of powders, flakes, platelets,microspheres, whiskers, bubbles, fiber mats and ceramic-coated fillers.5. A metal matrix composite injection molding tool for plastic materialscomprising:a metal matrix composite material base portion; at least oneforming surface integral to said base portion, said at least one formingsurface comprising a textured surface; at least one heating or coolingchannel within said base portion and communicating with an area externalto said base portion; and at least one wall portion of at least one of agate or a sprue extending through said base portion, said at least onewall portion comprising protrusions, wherein said protrusions introduceturbulence into a thermoplastically deformable material during flow ofsaid thermoplastically deformable material in said at least one of agate or a sprue.
 6. The metal matrix composite injection molding tool ofclaim 5, wherein said metal matrix composite material base portioncomprises an aluminum matrix metal and a silicon carbide fillermaterial.
 7. The metal matrix composite injection molding tool of claim5, wherein said metal matrix composite material base portion comprisesat least one matrix selected from the group consisting of aluminum,bronze, and cast iron and at least one filler is selected from the groupconsisting of powders, flakes, platelets, microspheres, whiskers,bubbles, fiber mats and ceramic-coated fillers.
 8. An injection moldingtool for plastic materials comprising:a metal matrix composite coresection; a metal matrix composite cavity section having at least onesurface defining at least one of a gate or sprue comprisingprotuberances, wherein said protuberances introduce turbulence into saidplastic material during flow of said plastic material in or through saidgate or sprue; and at least one cooling channel in at least one of saidcore section and said cavity section, wherein said at least one coolingchannel is proximately located to the plastic material during injectionof said plastic material.
 9. The injection molding tool of claim 8,wherein at least one of said metal matrix composite core section andsaid metal matrix composite cavity section comprise an aluminum matrixmetal and a silicon carbide filler material.
 10. The injection moldingtool of claim 8, wherein at least one of said metal matrix compositecore section and said metal matrix composite cavity section comprise atleast one matrix selected from the group consisting of aluminum, bronze,and cast iron and said at least one filler is selected from the groupconsisting of powders, flakes, platelets, microspheres, whiskers,bubbles, fiber mats and ceramic-coated fillers.
 11. The injectionmolding tool of claim 8, wherein said at least one cooling channel islocated in each of said core section and said cavity section.
 12. Theinjection molding tool of claim 8, wherein said at least one surfacedefining at least one of a gate or sprue comprises protuberances whichintroduce turbulence into the plastic material during flow of saidplastic material in said at least one of a gate or a sprue.